Preheat your oven to 350°F and line a 9x9 inch baking pan with parchment paper. In a small saucepan, melt the butter over low heat, then stir in the cocoa powder until smooth. This step prevents lumps and gives you silky brownie batter. Remove from heat and let it cool for about 2 minutes.

Mix both sugars together in a medium bowl, then add the cooled cocoa mixture and stir well. Add the eggs one at a time, stirring after each addition so they incorporate fully. The mixture should look thick and glossy. Pour in the milk and vanilla bean paste, stirring until everything comes together.

In another bowl, whisk together the flour and a pinch of salt. Fold the dry ingredients into the wet mixture gently — you'll want about 20 folds with a rubber spatula. Don't overmix or you'll end up with dense brownies. Fold in the chocolate chips last so they distribute evenly.

Pour the batter into your prepared pan and spread it to the edges evenly. Bake for 28-30 minutes until a toothpick inserted in the center comes out with just a few moist crumbs. Let the brownies cool completely in the pan — this usually takes about 20 minutes. I always walk away and make coffee during this time because checking too early messes with the cooling process.

Once cool, cut the brownies into 16 squares (like a checkerboard pattern with 4 cuts each way). You'll have 8 pairs for your patriotic brownie ice cream sandwiches. Place half of them cut-side up on a clean surface, leaving space between each piece.

Soften the ice cream at room temperature for about 5 minutes until it's spreadable but not melting. Swirl the strawberry puree into 4 tablespoons of ice cream until it's marbled pink, then swirl the blueberry puree into another 4 tablespoons for blue streaks. Divide the remaining ice cream into plain portions for assembling.

Spread or scoop a generous portion of ice cream (mix of plain, pink, and blue swirls) onto each bottom brownie square. Top with the matching brownie square and press gently. Roll the edges in rainbow sprinkles for extra flair, then freeze on a baking sheet for at least 2 hours before serving. These frozen treats stay perfect in the freezer for up to 5 days.