Preheat the oven to 350 °F (175 °C). Line muffin pans with 16 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. Roll into 18-gram balls, flatten with your palm, and place in each muffin liner.
1/2 cup (100 grams) granulated sugar, 1/2 cup (62 grams) flour, 1/2 cup (58 grams) Dutch-process cocoa powder, 2/3 teaspoon baking powder, pinch salt, 6 tablespoons (84 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.
If using whole wheat or AP flour, bake for 11-13 minutes or until the crust no longer appears wet and move on to the next step. If using buckwheat, bake for 14 minutes.
After baking, the crust will still be soft but will firm up as it cools. Let cool for 10 minutes while you prepare the cheesecake. I turned off the oven for about 5 minutes and at that point, it was at 275 ºF (135 ºC), which is the temperature you need to bake the cheesecakes at. You can alternatively immediately turn the temperature down to 275 ºF (135 ºC) after removing the crusts.