Get Ready to Bake: Start by preheating your oven to 350°F (175°C). Lightly grease your angel food cake pan (the one with the tube in the middle), but resist the urge to flour it – this helps the cake climb high and airy!
Whip Up the Batter: In a large bowl, combine your angel food cake mix with the cold water, optional lemon juice, and vanilla extract. Using a hand or stand mixer, beat on high speed for about 2 minutes until the mixture forms lovely stiff peaks. This creates that signature light and fluffy texture!
Fold in the Berries: Gently, with a spatula, fold in the fresh raspberries. Be careful not to overmix, as we want those beautiful berries to stay intact and not crush, keeping the cake light and delicate. If using the optional 1/4 cup sugar, you can gently toss the raspberries with it before folding into the batter.
Time to Bake: Carefully pour your light and airy batter into your prepared cake pan. Give the pan a gentle tap on the counter to release any trapped air bubbles. Bake for 35 to 40 minutes, or until the top is golden brown and a toothpick inserted into the center comes out perfectly clean.
Cool Upside Down: This is a secret for angel food cake perfection! As soon as it comes out of the oven, immediately invert the pan onto a cooling rack or a sturdy bottle. Let it cool completely for about an hour – this prevents the cake from collapsing and keeps it wonderfully airy.
Release and Serve: Once fully cooled, gently run a thin knife around the edges of the cake and the inner tube to loosen it. Carefully remove the cake from the pan and transfer it to your prettiest serving platter. Now it’s ready for your Valentine’s celebration!