Plum Financiers

Adjust an oven rack to middle position and heat oven to 375 degrees. Generously spray 24-cup mini-muffin tin with baking spray with flour. Melt butter in 10-inch skillet over medium-high heat. Cook, stirring and scraping skillet constantly with rubber spatula, until milk solids are dark golden brown and butter has nutty aroma, 1 to 3 minutes. Immediately transfer butter to a heatproof bowl to cool slightly.

Whisk almond flour, sugar, all-purpose flour, and salt together in a second bowl. Add egg whites. Using a rubber spatula, stir until combined, mashing any lumps against the side of the bowl until the mixture is smooth. Stir in butter until incorporated. Distribute batter evenly among prepared muffin cups (cups will be about half full). Slice plum wedges crosswise ¼ inch thick. Shingle 2 slices on top of each cake (do not press into the batter). **

Bake until edges are well browned and tops are golden, about 14 minutes, rotating tin halfway through baking. Remove the muffin tin from the oven and immediately invert a wire rack on top of the tin. Invert the rack and tin together; carefully remove the tin. Turn the cakes right side up and let them cool for at least 20 minutes before serving.

**Feel free to substitute here: a fresh raspberry, a chunk of chocolate, a shingles of poached pear, apricot, peach, plumcot, a dab of raspberry jam, nutella, or ganache--really any other delicious tidbit.