Preheat your oven to 350°F (175°C) and line a baking sheet with parchment paper.
In a large bowl, cream together the softened butter, brown sugar, and granulated sugar until light and fluffy, about 3-4 minutes.
Add in the eggs one at a time, beating well after each addition, followed by the vanilla extract.
In another bowl, whisk together the flour, cocoa powder, baking powder, and salt.
Gradually add the dry mixture to the wet ingredients, mixing until just combined.
Fold in the chocolate chips gently, ensuring an even distribution.
Drop tablespoons of dough onto the prepared baking sheet, spacing them about two inches apart.
Bake in the preheated oven for 10-12 minutes, until the edges are set and the cookies appear slightly underbaked in the center.
While the cookies cool, prepare the chocolate ganache by melting chocolate and cream together until smooth.
Drizzle or spread the ganache over the cooled cookies and top with colorful sprinkles.