Preheat the oven according to the brownie mix instructions.
Prepare two boxes of brownie mix using the ingredients listed on the packages.
Line a 9×13 baking pan with parchment paper and spread the batter evenly.
Bake according to the box directions, then let the brownies cool completely.
Refrigerate the brownies for 1 hour until firm.
Use a heart-shaped cookie cutter to cut out brownie hearts and place them on a wire rack.
Add 1½ cups chocolate chips to a heatproof bowl.
Microwave ¾ cup heavy cream for 45–60 seconds until hot and steaming.
Pour the cream over the chocolate, let it sit for 2 minutes, then stir until smooth.
Let the ganache thicken for 5–10 minutes, then spoon it over the brownie hearts, letting it drip down the sides.
Melt white and pink chocolate wafers and drizzle over the brownies.
Add sprinkles right away and chill briefly until set.
Notes
Chill before cutting: Cold brownies cut much cleaner, especially when using a larger heart-shaped cutter.Use a straight press: Press the cutter straight down and lift straight up to keep the heart shape neat.Let ganache thicken slightly: If the ganache is too hot, it will run off completely. Waiting a few minutes helps it cling to the brownies.Decorate in layers: Let the ganache set before adding drizzles so the colors stay defined.Save the scraps: Brownie scraps are perfect for snacking, parfaits, or stirring into ice cream.