• Preheat the oven to 350°F (180°C) and prepare a 9”x13” (20cm x 30cm) pan by lining it with parchment paper, making sure there’s a slight overhang for easy removal.
• In a heatproof bowl over simmering water (without letting the bowl touch the water), melt the dark chocolate and butter, stirring until smooth. You can also do this in a microwave-safe bowl, heating in 30-second increments and stirring well each time.
• Sift the cocoa powder over the melted mixture and stir until fully incorporated.
• In a large bowl, beat the eggs, granulated sugar, and brown sugar with an electric handheld mixer on medium to high speed for 2-3 minutes until the mixture lightens in color and increases in volume. A stand mixer with a whisk attachment works too.
• Gently mix in the chocolate mixture, then add salt and vanilla extract until combined.
• Fold in the flour by hand until the batter is smooth and lump-free. Transfer it to the prepared pan, then tap the pan on the counter to release air bubbles. Let it sit for a minute, then tap again.
• Bake for 18-20 minutes, checking after 15 minutes. The edges should be set, and a skewer inserted in the middle should come out with a few moist crumbs—avoid overbaking.
• Once done, remove the brownies from the oven and let them stand for 5 minutes before preparing the icing ingredients.

Chocolate Icing for Cosmic Brownies

• Sift together the powdered sugar, cocoa powder, and salt into a bowl. This step ensures a smooth, lump-free icing. Add butter and mix until the dry ingredients coat it evenly.
• Once the brownie has rested for 5 minutes, pour in the boiling water. Stir the icing ingredients until the butter melts and the mixture is evenly combined. Start with a spatula, then switch to a whisk to bring everything together smoothly.
• Pour the hot icing over the brownie, using an offset spatula or the back of a spoon to spread it evenly. The heat from the brownie will help the icing melt and settle.
• Let the icing stand for 1-2 minutes, then top with sprinkles of your choice for that classic cosmic brownie look.
• Place the brownies in the fridge and allow them to chill completely for a few hours or overnight to set the icing properly.
• Once firm, remove the brownies from the pan using the parchment paper. Use a sharp knife to slice them into even pieces. Store in an airtight container in the fridge for up to 5 days for freshness.