Preheat the oven to 175 C. Grease an 8" springform pan and set aside.
Sift the flour and baking powder in a large bowl. Mix in the salt if using, then set aside.
Cream the butter and sugar till pale and fluffy, preferably using a hand mixer or stand mixer. Make sure you're using a large mixing bowl.
Add the eggs and vanilla beat well till combined.
Fold in the flour mixture, and beat until smooth and combined. Spoon the batter into the prepared tin and smooth it out. The batter is thick but spreadable.
Bake for 30 mins, then check to see if the top is browning too fast. If so, cover with aluminium foil and continue to bake for another 30 to 45 mins. A toothpick poked in the center must come out clean. Baking times will vary for this cake because it is a large, buttery batter, so keep a close watch on it.
Let the cake cool completely at room temperature, the place in the fridge for a couple of hours to firm up. This make it easier to slice and frost.
Peel the chilled mangoes (chilling keeps them firm) and slice as thinly as you can. Keep chilled while you make the frosting.
To make the frosting, beat the cream cheese, butter and sugar till smooth and fluffy. If you'd like it to be more buttery, or sweeter, you can adjust the quantities. Keep the frosting chilled while you slice the cake.
Unmould the cake, and using a sharp, long knife, slice it in half horizontally, turning it with your hands as you go, so that the cut is even. If the top is a little domed, level it off. Use a metal spatula to lift the top off and set it aside on a large tray or plate. Transfer the lower half to a serving platter.
Spoon about one-third of the frosting onto the lower half, spreading it evenly, taking care not to let it touch the edge or it'll spill over when you place the top half on it. Arrange the mangoes in concentric circles.
Now gently place the top half on the mangoes and press down lightly to help push the frosting to the edges. Spoon the remaining frosting on top of the cake, smoothen it out and repeat the mango arrangement. Cherries make a fun garnish!
Chill the ready cake for about 30 minutes. Then use your sharpest knife and slice it into 8 large pieces. Store the cake in the fridge at all times, where it will keep for 3 to 4 days. Let it come to room temperature before eating. Fresh mangoes don't last very long so some discolouration might occur which is why this cake is best eaten by day two. For smaller cake sizes, see the notes below. Happy baking!