Chocolate Brownie Cookies

Position an oven rack on the center rung. Heat the oven to 350°F and line two baking sheets with parchment (or grease and flour the pan).

In a double boiler over simmering water, melt the butter and chocolate. Stir to combine; let cool. In an electric mixer with the whisk attachment, beat the eggs and sugar on medium high to a ribbon consistency, 3 to 4 min. Take the bowl off the mixer. Add the cooled chocolate mixture and the vanilla; stir to combine. Sift the flour, baking powder, and salt together. Stir the flour mixture and the nuts into the batter; let the batter rest for 5 min.

Spoon the batter into a pastry bag fitted with a #4 tip (or into a heavy-duty zip-top bag with one bottom corner snipped to create a 2/3-inch diagonal opening). For each cookie, pipe 1 Tbs. batter onto the lined baking sheet. While you pipe the second tray, bake the first until the cookies are puffed and cracked and the tops barely spring back when pressed, 8 to 10 min. The cracks should be moist but not wet. Cool the cookies on a wire rack.