Fold 3 paper towels into a 1 1/2-inch by 1 1/2-inch square and place one into each of the paper cups to support the cupcake paper. Place a cupcake paper in each paper cup on top of the paper towel.
Combine the angel food cake mix with 3/4 cup cold water and whisk for 30 seconds until well combined and the batter is thick and slightly fluffy.
Fill each cupcake paper-lined cup halfway with the cake batter. Microwave the cakes for 1 minute on high. Let cakes cool 2 minute before removing from the cups but leave in the cupcake paper. Repeat the process with the remaining batter.
Place heavy cream into a large bowl and put into freezer for 10 to 15 minutes before you are ready to whip it. Beat with an electric hand mixer until just before soft peaks. Add the dulce de leche and beat until well incorporated and soft peaks form.
To serve, gently remove the cupcake papers from the cakes. Place the cake upside down on a plate, top with a dollop of the whipped cream and sprinkle with some raspberries, blueberries and top with mint. Repeat with the remaining cakes.