105 g flour (2/3 cup
4 g cornstarch (1 teaspoon)
100 g sugar (1/2 cup)
65 g cocoa powder, preferably valhrona (2/3 cup) 4 g kosher salt (1 teaspoon)
85 g butter, melted (6 tablespoons)
1. Heat the oven to 300°F.
2. Combine the flour, cornstarch, sugar, cocoa powder, and salt in the bowl of a stand mixer fitted with the paddle attachment and paddle on low speed until mixed.
3. Add the butter and paddle on low speed until the mixture starts to come together in small clusters.
4. Spread the clusters on a parchment-or Silpat-lined sheet pan. Bake for 20 minutes, breaking them up occasionally. The crumbs should still be slightly moist to the touch at that point; they will dry and harden as they cool.
5. Let the crumbs cool completely before using in a recipe or eating. Stored in an airtight container, they will keep fresh for 1 week at room temperature or 1 month in the fridge or freezer.