01 - Cream softened butter and brown sugar in a small bowl until light and fluffy. Whisk in milk and vanilla extract. Stir in heat-treated flour and salt until fully incorporated. Fold in mini chocolate chips. Scoop 12 portions (approximately 2 teaspoons each), roll into balls, and place on parchment-lined plate. Refrigerate until firm.
02 - Combine butter and chopped dark chocolate in a heatproof bowl. Microwave in 30-second intervals or melt over double boiler, stirring until completely smooth. Allow mixture to cool slightly before proceeding.
03 - Beat granulated sugar, brown sugar, and eggs in a large mixing bowl for approximately 2 minutes until mixture becomes pale and creamy. Add vanilla extract and melted chocolate mixture, stirring until thoroughly combined.
04 - Whisk together flour, cocoa powder, baking powder, and salt in a separate bowl. Gradually add dry ingredients to wet mixture, stirring until thick, fudgy dough forms. Refrigerate dough for 10-15 minutes to facilitate handling.
05 - Set oven to 350°F. Line two baking sheets with parchment paper and set aside.
06 - Portion approximately 2 tablespoons of brownie dough per cookie. Flatten dough in palm of hand. Place one chilled cookie dough ball in center and wrap brownie dough completely around filling, sealing edges securely. Repeat until all cookies are formed.
07 - Arrange cookies on prepared baking trays, leaving adequate space between each. Bake for 10-12 minutes until tops appear set with characteristic crackled surface. Remove promptly to maintain fudgy texture.
08 - Let cookies rest on baking sheets for 10 minutes before transferring to wire rack to cool completely. This allows structure to set while maintaining soft center.