Whisk the dry ingredients. In a medium bowl, whisk flour, cocoa, baking powder, baking soda, salt, and espresso powder. Set aside.

Melt the chocolate. In a heatproof bowl, melt the chocolate chips gently in the microwave in 20–30 second bursts, stirring between each, until smooth. Cool 3–4 minutes so it’s warm, not hot.

Mix the wet ingredients. In a large bowl, whisk oil, granulated sugar, brown sugar, milk, yogurt, and vanilla until glossy and well combined.

Combine with chocolate. Stir the melted chocolate into the wet mixture until uniform and shiny.

Add dry to wet. Use a spatula to fold the dry mixture into the wet just until no dry streaks remain. The dough will be soft and thick, like brownie batter.

Chill the dough. Cover and refrigerate for at least 1 hour (2 hours is even better). This firms the dough so it rolls cleanly and helps the cookies puff and crack.

Prep the coating. Place granulated sugar in one shallow bowl and powdered sugar in another. Line two baking sheets with parchment and preheat the oven to 350°F (175°C).

Scoop and roll. Scoop heaping tablespoon portions (about 30 g each). Roll into balls, then coat each ball first in granulated sugar and then generously in powdered sugar. Aim for a thick powdered layer.

Space and bake. Arrange on baking sheets 2 inches apart. Bake 10–12 minutes, until the cookies are puffed, the tops are cracked, and the edges look set but centers are still soft.

Cool for texture. Let cookies cool on the sheet for 10 minutes, then transfer to a rack. They’ll finish setting as they cool while staying fudgy inside.