Pre-heat your oven to 325F and line the bottom of 3 9-inch round pans with parchment paper. Do not grease.
In a large bowl, whisk 2 1/4 cups cake flour, 1 1/4 cups sugar, 1 tablespoon baking powder and 1 teaspoon salt until combined. Set aside.
Using a handheld electric mixer or a stand mixer with the paddle attachment, beat 5 egg yolks, 3/4 cup water, 1/2 cup canola oil, 1 teaspoon lemon zest and 1 teaspoon vanilla on high speed until smooth and creamy (about a minute). Set aside.
Using a handheld electric mixer or a stand mixer with the whisk attachment (if using the same mixers, ensure they are clean, dry and grease-free), beat 8 egg whites and 1/2 teaspoon cream of tartar on medium speed until you reach soft peaks (about 1-2 minutes). Then switch to high speed and gradually add 1/4 cup sugar. Beat until the egg whites are very stiff and dry (about 5 minutes).
Whisk your egg yolk mixture into your flour mixture until smooth and incorporated.
Then fold your egg whites into your batter in thirds. Gently fold until each addition is incorporated.
Transfer the batter equally into your 3 pans and bake for 30 minutes or until the top springs back when lightly pressed and a toothpick inserted in the centre comes out clean.
Run a sharp knife along the sides of each cake and allow to cool in the pan for 10 minutes. Then unmold and transfer to a wire rack to cool completely.
For the Whipped Mango Cream Frosting:
Pour 1 packet of unflavoured gelatine into 1/4 cup cold water. Do not stir. Let sit for 10 minutes to allow it to bloom.
In the meantime, using a handheld electric mixer or a stand mixer fitted with the whisk attachment, whip 2 cups heavy cream, 2 tablespoons sugar and 2 teaspoons vanilla on medium high speed until you reach soft peaks.
Get your gelatine and microwave for 10 seconds. Whisk until smooth (it shouldn't be warm to the touch). With the mixer still on, gradually pour it in a steady stream into your whipped cream. Continue whipping until the gelatine is incorporated.
Add 1 cup mango puree and whip the cream until you reach stiff peaks or you get the consistency you want.
Take about a cup of your whipped frosting and combine with your chopped mangoes. Divide the mixture into two.
Evenly spread half of the mixture on top of the first cake layer. Put on the next cake layer and spread the rest of the mixture on top of that. Put the last cake layer on and proceed to cover the rest of the cake with whipped frosting and decorate as desired.
Chill for at least 3 hours before serving.
I used store-bought mango puree. If you're making your own, you can use a blender or food processor to puree about about 4 mangoes then strain to ensure the smoothest mixture.