1. Prepare the Butterbeer Brownie Batter

1. Preheat oven to 350°F (177°C) and line a 9×13-inch baking dish with parchment paper.
2. In a saucepan over low heat, melt butter and stir in sugar until combined. Remove from heat.
3. Whisk in eggs, vanilla extract, and cream soda, ensuring a smooth mixture.
4. In a separate bowl, mix flour, cocoa powder, salt, and baking powder.
5. Gradually fold dry ingredients into the wet mixture, stirring until just combined.

2. Bake the Brownies

6. Pour the batter into the prepared pan, spreading it evenly.
7. Bake for 25-30 minutes, or until a toothpick inserted in the center comes out with a few moist crumbs.
8. Let brownies cool completely before adding the glaze.

3. Make the Blueberry Swirl Glaze

9. In a small saucepan over medium heat, cook blueberries, sugar, and lemon juice until the berries break down.
10. Stir in the cornstarch slurry and cook for another 1-2 minutes, until the mixture thickens.
11. Divide the glaze into two portions and tint one with blue gel food coloring and the other with purple.

4. Create the Starry Night Effect

12. Spread the blue and purple blueberry glaze over the cooled brownies in swirling patterns.
13. Use a fine brush to paint white stars and constellations with edible paint or melted white chocolate.

5. Set & Serve

14. Let the glaze set for 15-20 minutes before slicing.
15. Serve and enjoy your magical Ravenclaw dessert!