Easy Valentine's Heart Brownies with Brownie Mix

0 Preheat and prep the pan. Preheat the oven according to your brownie mix box directions and line your baking pan with parchment paper (this is the easiest way to lift out the baked brownies cleanly).
1 Mix the brownie batter. In a large bowl (or the bowl of a stand mixer if you prefer), combine the brownie mix with the eggs, oil, and water (or coffee), plus a splash of vanilla extract if desired; mix just until combined to avoid cakey brownies. *Note: don't forget to use the ingredients your specific brownie mix calls for if you're not using the brand I use.
2 Bake the brownies. Pour the brownie batter into the prepared pan and bake until set according to package instructions; use a cake tester to check doneness (you want moist crumbs, not wet batter).
3 Cool completely. Let brownies cool to room temperature before cutting; warm brownies will crumble and you’ll lose the heart shape.
4 Cut into hearts. Lift the cooled brownies out and place on a cutting board, then press a cookie cutter into the brownies to create heart-shaped brownies.
5 Make the chocolate ganache (optional). Add chocolate chips and butter to a heat-safe bowl, warm the milk until steaming (not boiling), then pour over the chocolate mixture; let sit for 2–3 minutes, then stir until smooth and glossy (if it’s too thick, stir in a tiny splash of warm milk; if it’s too thin, let it sit for a few minutes to thicken as it cools).
6 Make the pink frosting (optional). Tint vanilla frosting with gel food coloring or natural food dye until you reach your desired pink shade, then spread on top of the brownie hearts or pipe on using a piping bag.
7 Decorate and serve. Spoon ganache over the top of the brownies or frost them, then finish with Valentine sprinkles.