Preheat the oven to 350?F (175?C). In a mixing bowl, whisk together the sugar, melted butter, eggs, and vanilla extract until smooth.

Sift in the cocoa powder, flour, salt, and baking powder. Mix until just combined. Pour the batter into a greased 8x8 inch baking dish.

Bake for 15-20 minutes or until a toothpick comes out with a few moist crumbs. Let cool completely before cutting into small squares.

In a large mixing bowl, cream together the softened butter, granulated sugar, and brown sugar until light and fluffy.

Add the vanilla extract and eggs, mixing until well combined.

In another bowl, whisk together the flour, baking soda, and salt. Gradually add the dry ingredients to the wet ingredients, mixing until just combined. Fold in the chocolate chips.

Take a small amount of cookie dough and flatten it in your palm. Place a brownie square in the center and wrap the dough around it, sealing it completely.

Place the stuffed cookie dough balls on a baking sheet lined with parchment paper, spacing them apart.

Bake in the preheated oven for 10-12 minutes or until the edges are golden brown. Let cool on the baking sheet for a few minutes before transferring to a wire rack.