Mini Pistachio Cakes

To prepare cookies: Heat butter in a small saucepan over medium heat just until it comes to a boil. Remove from heat (you want to use the butter while it's still warm).

Place pistachios and sugar in a food processor and pulse until the nuts are ground but still slightly chunky; don't overprocess into a paste. Add all-purpose flour, whole-wheat flour, matcha and salt and pulse a few times to blend.

Whisk egg whites in a medium bowl. Add the nut mixture and stir with a flexible spatula until thoroughly blended. Gradually and gently incorporate the butter, stirring lightly—it will take a little while to get all the butter into the batter—until the batter is thick and shiny. Cover and refrigerate for at least 3 hours or up to 3 days.

Preheat oven to 400°F. Coat a mini muffin tin (24 mini cups) with cooking spray. Spoon the batter into the cups.

Bake the buttons until the edges are deeply golden and the tops have crowned and feel springy to the touch, 13 to 15 minutes. Let cool in the pan for 5 minutes, then turn out onto a wire rack. Let cool to room temperature, about 1 hour.

To prepare glaze: Place chocolate and oil in a small microwave-safe bowl. Microwave on Medium in short bursts until the chocolate has melted, 1 1/2 to 3 minutes. (Alternatively, melt chocolate and oil in a double boiler.)

If you want to add color to the glaze, mix the melted chocolate with up to 1/2 teaspoon matcha or raspberry powder—add it gradually until you get the shade you want.

Dip the tops of the buttons in the chocolate glaze, then place them on a baking sheet and refrigerate until the chocolate hardens. about 30 minutes. If you want to sprinkle the tops with matcha (or raspberry powder), do it before the glaze sets.