Makes: About 4 full-sized and 4 mini sandwiches
About 2 tablespoons softened butter (I liked salted), for pan
About 2 tablespoons all-purpose flour, for pan
2 sticks plus 2 tablespoons/9 ounces/255 grams unsalted butter, softened
1½ cups/300 grams granulated sugar
1/2 teaspoon kosher salt
6 whole large eggs, cracked into a measuring cup with a spout
1 cup/4 ounces/113 grams almond flour
1 teaspoon almond extract
1 cup/4 ounces/113 grams sifted cake flour
2 tablespoons sliced almonds
Buttercream, recipe follows
1. Prep: Lightly butter a half-sheet (18x13x1-inch) pan. Line with parchment paper. Butter and flour parchment. Tap out any excess flour. Set rack in the upper third of oven. Heat oven to 325F (conventional) or 300F (convection).
2. Mix: Drop butter into the bowl of a stand mixer fitted with the paddle attachment. Beat fluffy, about 2 minutes, stopping to scrape down sides of the bowl as needed. Still beating, cascade in sugar and salt. Beat fluffy. Slide in eggs, one at a time, beating fluffy after each. Beat in almond flour and extract. Total beating time: about 4 minutes.
3. Fold: Pull bowl off stand. Sift cake flour (again!) over the batter and, using a soft spatula, fold in gently.
4. Bake: Scrape batter onto prepared sheet pan. Smooth evenly with an offset spatula. Scatter on sliced almonds. Bake until golden and springy, about 20-21 minutes. Cool completely in pan.
5. Cut: When cool, punch out (or freehand) bread-slice shapes. Spread the sliced-almond side of one slice with buttercream. Top with a second slice, almonds-down. Repeat, composing all sandwiches. Chill. Cut sandwiches in half on the diagonal. Slip each into a waxed paper bag. Makes a wholesome lunch.
Chocolate Buttercream
2 ounces bittersweet chocolate
6 ounces/1½ sticks/170 grams softened unsalted butter
1 pinch salt
2 large egg whites
7 tablespoons/88 grams granulated sugar
1½ teaspoons espresso powder dissolved in 1½ teaspoons coffee
½ teaspoon vanilla extract
1. Prep: Break up chocolate into a microwave-safe bowl. Zap 1 minute to melt. Stir smooth. Let cool. Drop butter into the bowl of a stand mixer. Toss in salt. Beat fluffy. Set butter aside. Make sure mixer bowl is perfectly clean and dry before starting next step.
2. Heat: Slide egg whites into the bowl of a stand mixer. Pour in sugar. Set this bowl over a pan of simmering water. Whisk until egg mixture looks foamy and reaches 165F, about 5 minutes.
3. Whip: Carefully wipe the bottom of the bowl dry, and snap it onto the stand mixer. Whisk on high speed to fluffy, glossy peaks, about 5 minutes. Reduce speed to medium and whisk in the fluffy butter, a few tablespoons at a time. Whisk in the chocolate. Whisk in espresso and/or vanilla.