Preheat the oven to 350°F (175°C) and position the oven rack in the center.

In a large mixing bowl, combine the angel food cake mix, water, fresh key lime juice, and vanilla extract. Beat on high speed for about 3 minutes.

Pour the batter into an ungreased tube pan and smooth the surface. Tap lightly to eliminate air bubbles.

Bake for 35–40 minutes, or until golden brown and springs back when touched. Check doneness with a toothpick.

Invert the pan over a bottle and cool upside down for 1–2 hours.

Run a thin knife around the edges to loosen the cake. Carefully remove from the pan.

In a chilled bowl, whip heavy cream and powdered sugar until soft peaks form, about 3–5 minutes.

Spread whipped cream over the cooled cake and garnish with lime slices and zest. Serve and enjoy!