Preheat your oven to 350°F or 175°C.
Melt the chocolate and butter in a double boiler or heat-proof bowl over a pan with an inch of water and let it cool slightly as you make the cookies.
10 ounces (283 grams) bittersweet chocolate, 4 tablespoons (2 ounces or 57 grams) unsalted butter
Whisk together the flour, cocoa powder, baking powder, and salt into a small bowl.
½ cup (2.2 ounces or 63 grams) bleached all-purpose flour, ¼ cup (0.8 ounces or 24 grams) unsweetened cocoa powder, ½ teaspoon baking powder, ½ teaspoon salt
In the bowl of your stand mixer or medium-sized bowl if you are using a hand mixer, beat the sugar and eggs together on medium speed for about four to five minutes until it is light yellow in color.
1 cup (7.1 ounces or 200 grams) granulated sugar, 3 large eggs
Add the vanilla extract and beat on medium speed for one minute.
1 teaspoon vanilla extract
Add in the melted chocolate and beat until mixed.
Add the dry ingredients and mix on low or by hand just until the dry ingredients have been combined.
Stir in the chocolate chips by hand.
1 cup semi-sweet or bittersweet chocolate chips
Put the bowl in the refrigerator for 15 to 30 minutes to make the batter easier to scoop. Meanwhile, line two baking sheets with parchment or silicone mats.
Put the powdered sugar into a small bowl, and use a medium-sized cookie scoop or two spoons to scoop out 1.5 tablespoons of cookie dough into the bowl. Toss with the powdered sugar and put on the baking sheet.
1 cup powdered sugar
Repeat with the rest of the brownie cookie dough, leaving 1 to 2 inches between cookie balls.
Bake for about 9 to 10 minutes. The tops will be cracked, and the cookies should still be slightly soft.
Let the cookies cool fully on the cookie sheet.