For the Cake:
1. Preheat the Oven: Preheat your oven to 350F (175C). Grease and flour three 8-inch round cake pans.
2. Prepare the Cake Batter: In a large bowl, cream together the softened butter and sugar until light and fluffy. Add the eggs one at a time, beating well after each addition. Mix in the vanilla extract, orange zest, and lemon zest.
3. Combine Dry Ingredients: In a separate bowl, whisk together the flour, baking powder, and salt. Gradually add the dry ingredients to the wet mixture, alternating with the milk. Beat until just combined.
4. Bake the Cakes: Divide the batter evenly between the three prepared cake pans. Bake for 25-30 minutes, or until a toothpick inserted into the center of the cakes comes out clean. Allow the cakes to cool in the pans for 10 minutes, then transfer to a wire rack to cool completely.

For the Citrus Cream Frosting:
1. Make the Frosting: In a large chilled bowl, beat the heavy whipping cream, powdered sugar, vanilla extract, orange juice, and lemon juice until stiff peaks form.

For Assembly:
1. Assemble the Cake: Place the first cake layer on a serving plate. Spread a layer of citrus cream frosting on top, then add a portion of the orange, lemon, and lime slices. Repeat with the second layer, adding frosting and fruit. Place the third cake layer on top and spread a thick layer of frosting over the entire cake.
2. Decorate the Cake: Arrange the remaining fruit on top of the cake, creating a colorful and vibrant display. Garnish with fresh mint leaves.