Make the cake:
Spray a 9-inch nonstick spring form pan with nonstick cooking spray. Preheat the oven to 350 degrees F.
Beat the egg whites on high with an electric mixer until soft peaks form. Add the granulated sugar gradually. Keep beating while you add the vanilla extract and the baking powder for 2 more minutes. Manually fold in the pecans and Ritz or Maria (or other) crackers. Transfer to the prepared pan. Bake for 30 - 35 minutes, until golden. Remove cake from the oven and let it cool down for 20 - 25 minutes.
Make the cream:
Using the electric mixer, beat the cream cheese, sour cream, powdered sugar, and vanilla extract (or lemon zest) until soft peaks form and the mixture is smooth.
Assemble the cake:
Remove the spring form pan. Using a spatula, evenly spread the cream all over the top of the cake. Garnish with the cubed or sliced mango. Serve and enjoy!