To bloom the cocoa powder, melt the butter in a medium saucepan over medium-low heat (or microwave). As soon as it’s melted, remove from heat and vigorously whisk in the cocoa powder and espresso powder for about 60 seconds until thick and glossy.
¾ c. butter, ¾ c. unsweetened natural cocoa powder, 1 tsp espresso powder
To a large mixing bowl, add 2 cups of granulated sugar. Transfer the cooling chocolate mixture and beat for 2-3 minutes.
2 c. granulated sugar
Once the mixture is just slightly warm, add eggs one at a time, beating well after each, then mix in the vanilla.
4 large eggs, 2 tsp vanilla extract
In a separate bowl, whisk together flour, baking powder, and salt. Add dry ingredients to wet and mix just until combined. Fold in mini chocolate chips.
2 c. unbleached all purpose flour (RECOMMEND WEIGHING), 2 tsp baking powder, ½ tsp salt, 1 c. mini semi-sweet chocolate chips
Cover and refrigerate at least 4 hours or overnight (overnight is best for easiest rolling and best crinkle effect).
Preheat oven to 350°F (175°C). Line baking sheets with parchment paper.
Scoop chilled dough with a 1 ½ tbsp scoop (#40 or similar), roll into balls (lightly oil or wet hands if sticky).
Roll each ball first in granulated sugar, then generously in powdered sugar.
¼ c. granulated sugar, ½ c. powdered sugar
Place 2 inches apart on sheets and bake 10–12 minutes — edges set, centers still soft. Do not overbake!
Cool on the baking sheet 5 minutes, then transfer to a wire rack.
Notes
Natural cocoa (not Dutch-process) is important for the best crackle effect.
Dough can be frozen up to 3 months: 1st scoop, then roll in granulated sugar only. Flash-freeze dough and place in bag. To bake: Roll frozen balls in powdered sugar and let thaw before baking. Lightly press dough down with your palm to get that beautiful crackle effect.
Store baked cookies in an airtight container up to 4 days or freeze up to 3 months.