Preheat the oven to 350 °F (175 °C). Line a regular-sized muffin pan with 12 muffin liners. Note that this crust recipe does not work in a regular pie pan – only as mini cheesecakes.
In a medium mixing bowl, stir together the dry crust ingredients (sugar through salt). Then stir in the melted butter until totally combined. If it's sticky and hard to handle, let it sit for about 5 minutes. Use a small cookie scoop to scoop out a ball of dough. Roll into twelve 18-gram balls, flatten with your palm, and place in each muffin liner.
6 tablespoons (75 grams) granulated sugar, 6 tablespoons (49 grams) flour, 6 tablespoons (43 grams) Dutch-process cocoa powder, 1/2 teaspoon baking powder, pinch salt, 4 1/2 tablespoons (63 grams) unsalted butter
Press down the crusts, if necessary, so that they reach the edge of the liner.
Bake for 3 minutes, turn the pan 180 degrees and bake for another 4 minutes. They'll be very, very soft and appear uncooked but the very top surface should appear baked and not doughy. Don't bake them too long - if they start bubbling, they've baked too long, and they fry and get weird.
Remove from the oven and let cool for 10 minutes while you prepare the cheesecake.
Turn the temperature down to 275 ºF (135 ºC) after removing the crusts.