Last Thursday marked the first “birthday” of A Sage Amalgam. True to form, I totally forgot about the date until around nine that night, so I certainly wasn’t starting a cake then. (Seriously, I’m notoriously bad about remembering birthdays — thank goodness for Google calendar reminders!) My absolute favorite cake is a white or yellow cake with white frosting (confession: I still enjoy the super sweet shortening-based ones from time to time) finished with a generous amount of coconut.
Several years back, tired of paying ten bucks (or more) for four, less-than-stellar gluten-free cupcakes, I set out to make my own. In fact, the above combination was the exact one I first attempted to make gluten-free. They were awful. Dense, oddly textured from the brown rice flour and mayonnaise (yes, mayonnaise), and lacking in flavor. The only saving grace was the frosting (and coconut), no joke. Needless to say, as someone who’s loved from-scratch baking since early childhood, I was bummed.
Happily, a lot has changed since then. About two years before launching the blog in its current form, I figured out a mix of flours and starches — millet and garbanzo-fava flour, potato and arrowroot starch — that, when baked, mimic the taste AND texture of all-purpose flour. (You’ll notice that I use those four items all.the.time. in my baked good recipes.) Yes, I still have recipe flops — for instance, this cake took more attempts to get just right (milk vs. buttermilk, canola oil vs. butter, 2/3 cup vs. 3/4 cup, on and on) than I care to count — but the process is really fun for me. And still, I absolutely refuse to post just so-so recipes that may-or-may not work for you — hence why I’m all about giving ingredient weights (still the absolute best way to ensure repeatability), and am more than happy to disclose what my ingredient sources are.
But back to this cake. While I’d normally make 1.5 times the buttercream and skip the lemon curd, I was feeling sentimental. As you can probably imagine, one-upon-a-time (when we were signed up for cable and got the Food Network — thank goodness for bunny ears and Hulu!) I regularly tuned in to watch Good Eats. So, in honor of the final episode airing on the tenth, I deemed it appropriate to make an Alton Brown recipe — lemon curd — with a twist of my own, of course. This cake is an homage to the Lemon-Coconut cake from Flames — a local diner and bakery — except on a much, much smaller scale (no exaggeration, one slice of theirs is about equal in size to at least half of this entire cake). The sweet-tangy-tropical flavor combination is a fantastic way to brighten up the long, mid-winter months.
Thank you to all the readers and supporters — here’s to a fun- and flavor-filled [second] year ahead!
White Cake with Meyer Lemon Curd Filling and Lemony Swiss Meringue Buttercream
Preparation Time: 1 1/2 hours
Inactive Preparation Time: 1 1/2 hour+
Baking Time: 35 – 45 minutes (mine took 40)
Serves: 6 or more
- 128 grams (2/3 cup) granulated white sugar¹
- 37 grams (1/4 cup plus 2 1/2 teaspoons) millet flour (plus more for the pan)
- 37 grams (1/4 cup plus 2 1/2 teaspoons) garbanzo fava bean flour
- 48 grams (1/4 cup) potato starch
- 19 grams (2 tablespoons plus 1 teaspoon) arrowroot starch
- 1/2 teaspoon xanthan gum
- 1 teaspoon baking powder
- 1/4 teaspoon Kosher salt
- 43 grams (3 tablespoons) unsalted butter, softened (plus more for the pan)¹
- 2 large egg whites
- 85 grams (6 tablespoons) whole milk
- 5 grams (1 teaspoon) vanilla extract
Meyer Lemon Curd Filling:
- 46 grams (1/4 cup) granulated white sugar
- 1/4 teaspoon (from 1 lemon) Meyer lemon zest, packed (use a Microplane rasp)
- 28 grams (2 tablespoons) Meyer lemon juice
- 2 large Egg Yolks
- 28 grams (2 tablespoons) cold unsalted butter, cubed
- 2 large egg whites, room temperature
- 96 grams (1/2 cup) granulated white sugar
- 1/8 teaspoon fine sea salt
- 99 grams (7 tablespoons) unsalted butter, softened²
- 1 tablespoon cooled lemon curd (from recipe above)
Coconut and Finishing Touches:
Preheat oven to 350°F. Grease a 6″ by 3″ tall round cake pan with removable bottom with butter and dust with millet flour (tap out excess); set aside.
Combine sugar through Kosher salt in the bowl of a stand mixer, whisk to combine. Add butter, fit mixer with paddle attachment and turn to medium-low. Blend until mixture resembles fine breadcrumbs (there won’t be any butter lumps like pie or tart crusts). Mix together egg whites through vanilla extract in a small, spouted bowl or measuring cup. With mixer running on medium, pour in liquid ingredients. Blend for about 1 minute or until mixture is smooth and forms ribbons that take about 30 seconds to dissolve.
Pour batter into prepared pan, smooth top. Place in preheated oven and bake for 35 – 45 minutes (mine took 40), or until a toothpick inserted in the center comes out clean. Allow cake to cool in the pan for 15 minutes before removing to a cooling rack.
Make Lemon Curd:
While the cake cools, make lemon curd filling. Bring about 1″ of water to a simmer in a small saucepan set over medium heat (I used my 2 quart All-Clad saucepan). While water warms, combine sugar and lemon zest in the bowl of a food processor; pulse to combine/chop up zest more (you can skip this step, but zest pieces will be larger). In a small, stainless steel bowl that fits on top of the saucepan, without touching the water, whisk together lemon-sugar, juice and egg yolks (I used my 2 quart stainless bowl by RSVP Endurance). Place bowl with egg mixture over simmering water; heat, whisking constanlty, until the mixture coats the back of a spoon and it reaches 155°F (about 3 minutes). Still over heat, whisk in about a quarter of the butter at a time — fully incorporate each before adding another. Carefully remove bowl to several layers of kitchen towels, dry off exterior very well. Immediately transfer lemon curd to a mason jar or other small, heatproof container, whisk to cool. Once cooled to room temp, cover top directly with plastic wrap, followed by a lid. Refrigerate until ready to use.
DO AHEAD: Lemon curd may be made several days in advance, just be sure to eat it all within seven days.
Bring about 1″ of water to a simmer in a small saucepan set over medium heat (I used my 2 quart All-Clad saucepan). In a small, stainless steel bowl that fits on top of the saucepan, without touching the water, whisk together egg whites, sugar and salt (I used my 2 quart stainless bowl by RSVP Endurance). Place bowl with eggs over simmering water; heat, whisking often, until they reach 120°F (about 5 – 7 minutes). Carefully remove bowl to several layers of kitchen towels, dry off exterior very well.
Pour egg white mixture into the bowl of a stand mixer, fit with whisk attachement and beat on high speed until firm-ish peaks form (about 5 – 7 minutes). Drop a scant tablespoon of softened butter into meringue mixture, beat on medium-high speed until fully incorporated. (You’re essentially making an emulsification, just like mayonnaise or hollandaise, so it’s important to add the fat very slowly, especially those first few additions. For a while, it won’t look like much of anything, and if it begins to separate (appear kind of chunky-liquidy), just beat beat beat until it smooths out again and then continue adding the butter in smaller pieces, and more slowly than before. Please don’t be intimidated, it just takes patience more than anything else.) Turn off machine. Repeat process until all of the butter is used and the buttercream is smooth and somewhat fluffy. Scrape down bowl, add 1 tablespoon lemon curd and beat until smooth.
The following steps are somewhat easier if your cake has been chilled in the fridge first, but as long as the cake is completely cooled to room temp you will have success. If, when you cut into the cake it still feels warm in the center, go ahead and chill the cake for 30 minutes or so — otherwise you risk softening (melting) the filling and buttercream too much.
Trim any roundness off the top of cake so it’s level (freehand with a sharp breadknife or with the aid of a cake leveler — another great item to use a Michael’s 40% off coupon on). Cut cake into two layers and remove top layer (a cake lifter is helpful, but not totally essential). Place bottom half onto your serving platter, tuck several strips of wax paper underneath as pictured to keep the surface clean.
Fit a pastry bag with coupler and Wilton #12 tip; fill with several tablespoons buttercream. With tip opening parallel to the cake surface and about 1/2″ above, pipe a dam just around the edges (get closer to the edge than I did here). Spread remaining lemon curd in the middle of the dam. Top with the second layer (I usually flip the top layer so what was the top side of the cake is positioned in the middle, and the middle is the top). Squeeze any remaining buttercream from the pastry bag onto the top (doesn’t have to be neat) and use a small, offset spatula to spread it (add more as needed) into a light coating (crumb coat) on the top and sides. Place in the freezer for 5 minutes or so, just until crumb coat is firmed up to the touch. Once crumb coat is firm, spread remaining buttercream into a nice, even layer on the top and sides.
To make the sprinkle-filled number, print a 300pt, Helvetica numeral onto regular paper. Trace (using a ruler for the straight edges) onto a sheet of wax paper, cut out using an X-Acto knife or other craft blade. Place cutout number wherever you like on the buttercream-frosted cake to “tape off” the area. Coat top and sides of cake with coconut, pressing down lightly to adhere (you may want to do this over several sheets of wax paper so you can use the coconut that falls off to coat the cake). Remove number (use a toothpick to gently peel up corner), cover coconut-covered part with the wax paper sheet used to cutout the number and carefully fill in number with sprinkles, press down lightly to adhere. Serve immediately, or place in the refrigerate until ready to serve.
¹ If desired, for a slightly sweeter and more moist-yet-crumblier version, increase sugar to 144 grams (3/4 cup) AND butter to 57 grams (4 tablespoons) — please note: I’ve only tested it with both items adjusted, not just one or the other. I’m torn as to which version I prefer, both are very good.
² Can be reduced from 99 grams (7 tablespoons) to 85 grams (6 tablespoons).