Ingredients:

1/2 cup unsalted butter
12 ounces semi-sweet chocolate chips
1/2 cup granulated sugar
1/2 cup brown sugar, packed
2 large eggs
1 teaspoon vanilla extract
1 cup all-purpose flour
1/4 cup cocoa powder
1 teaspoon baking powder
1/2 teaspoon salt
Additional chocolate chips for filling
Directions:

Preheat the Oven:

Preheat oven to 350°F (177°C).
Prepare the Chocolate Mixture:

Melt butter and chocolate chips together; let cool slightly.
Combine Wet Ingredients:

Whisk together granulated sugar, brown sugar, eggs, and vanilla extract. Stir into the chocolate mixture.
Mix Dry Ingredients:

Sift in flour, cocoa powder, baking powder, and salt; fold to combine.
Chill the Dough:

Chill dough for 15 minutes for easier handling.
Form and Fill:

Form dough into balls, insert a few extra chocolate chips in the center of each, and place on a baking sheet.
Bake:

Bake for 10-12 minutes until the tops are glossy and cracked.
Cool:

Let cool on baking sheet for 5 minutes; transfer to a wire rack to cool completely.