Set out a medium heat-proof bowl because you’ll need it at the end of this step. Slice the butter into Tablespoon-size pieces and place in a light-colored skillet or saucepan. A light-colored interior is crucial for determining when the butter begins to brown. (See Notes if using a dark skillet or pan.) Melt the butter over medium heat and stir or whisk constantly. Once melted, the butter will begin to foam. Continue stirring/whisking, keeping a close eye on it. After about 5–7 minutes, the butter will begin browning and you’ll notice lightly browned specks forming at the bottom of the pan. The butter will have a nutty aroma. The color will gradually deepen, from yellow to golden to golden-brown; once it’s a light caramel-brown color, remove from heat immediately and pour into the bowl, including any brown solids that have formed on the bottom of the pan. Separate out 2 Tablespoons of brown butter—we’ll brush that in the muffin pans in step 2. Cool the remaining brown butter (about 1/2 cup) for 30 minutes in the refrigerator, or until room temperature and no longer warm. Don’t cool longer than that because the butter will begin to solidify.

Preheat the oven to 350°F (177°C). Using a pastry brush, brush the cups of a 24-count mini muffin pan with the 2 Tablespoons of browned butter. This recipe yields 30–36 tea cakes, so grease a 2nd pan or bake the batter in batches. If using mini muffin liners, brush the liners with the brown butter.

Using a hand mixer or a stand mixer fitted with a whisk attachment, whip the egg whites on high speed in a large bowl until soft peaks form, about 2–3 minutes. Add the almond flour, all-purpose flour, granulated sugar, baking powder, salt, and lemon zest. Beat on low speed until combined and don’t worry that the egg whites deflate, you’ll still taste their fluffy goodness in the cakes! Mixture will be sticky, lumpy, and thick. Pour in the vanilla extract and cooled brown butter and beat on low speed until combined.

Spoon 2 teaspoons of batter into each greased muffin cup. Lightly poke a berry into the center of each. No need to submerge the berry, just stick it on top.

Bake for 14–16 minutes or until the edges are golden brown. Remove from the oven and cool in the pan for 10 minutes before removing. Tea cakes will slightly deflate as they cool.

If desired, lightly sift confectioners’ sugar on warm or cooled tea cakes before serving.

Tea cakes are best enjoyed the day they are made. Store leftover tea cakes covered lightly at room temperature for up to 3 days or in the refrigerator for up to 1 week.