Preheat your oven to 350°F (175°C). Grease and flour an 8x8 inch baking pan or line it with parchment paper.
In a large bowl, whisk together the melted butter and granulated sugar until well combined.
Beat in the eggs one at a time, then stir in the vanilla extract.
In a separate medium bowl, whisk together the flour, cocoa powder, salt, and baking powder.
Gradually add the dry ingredients to the wet ingredients, mixing until just combined. Do not overmix.
Spread the batter evenly into the prepared baking pan.
Bake for 25-30 minutes, or until a toothpick inserted into the center comes out with moist crumbs attached.
Let the brownies cool completely in the pan on a wire rack.
While the brownies are cooling, prepare the toppings. Melt the white chocolate chips according to package directions. Melt the red and blue candy melts separately according to package directions.
Once the brownies are cool, drizzle the melted white chocolate over the top. Immediately drizzle the melted red and blue candy melts in stripes or swirls over the white chocolate. Sprinkle with patriotic sprinkles before the candy melts set.
Let the toppings set completely, then cut the brownies into squares and serve.
Notes
For extra fudginess, slightly underbake the brownies. Ensure all candy melts are fully set before cutting for clean lines.