Step 1: Preheat your oven to 350°F (175°C) and grease and flour two 9-inch round cake pans.
Step 2: In a large bowl, whisk together the cake flour, baking powder, baking soda, and salt.
Step 3: In another bowl, beat the softened unsalted butter and granulated sugar together until light and fluffy (about 3-5 minutes).
Step 4: Add the eggs one at a time, mixing well after each addition, then stir in the vanilla extract.
Step 5: Gradually add the dry ingredients to the butter mixture in three additions, alternating with the buttermilk, starting and ending with the flour mixture.
Step 6: Fold in the mango puree until just blended.
Step 7: Divide the batter equally between the prepared cake pans and bake for 25-30 minutes, or until a toothpick comes out clean.
Step 8: Once baked, let the cakes cool in the pans for about 10 minutes, then transfer to a wire rack to cool completely.
Notes
Make sure your butter is at room temperature for the best mixing results. Use fresh, ripe mangos for the puree to get the most flavor.