Preheat oven to 350°F (175°C) and line a 9×13-inch baking pan with parchment paper.

Whisk melted butter and sugar in a bowl until smooth and glossy.

Add eggs one at a time, mixing well after each addition. Stir in vanilla extract.

Sift cocoa powder, flour, salt, and baking powder into the bowl and fold gently until combined.

Stir in the chocolate chips.

Spread the batter evenly into the prepared baking pan.

Bake for 25–30 minutes until the edges are set and the center remains slightly soft.

Allow the brownies to cool completely in the pan.

Melt the white chocolate chips with coconut oil in the microwave using short intervals.

Divide melted chocolate into small bowls and mix each with pastel gel food coloring.

Drizzle the colored chocolate over the cooled brownies in decorative lines.

Let the drizzle set, slice into squares, and serve.