Grease the cake pan lightly. Line the bottom with parchment paper. This helps the cake release easily after baking and keeps the surface smooth.

Combine flour, baking powder and salt in a bowl. Stir well to distribute everything evenly. Set the mixture aside while preparing the wet ingredients.

Beat eggs and sugar until pale and fluffy. This step creates air in the batter. The cake will become lighter and softer after baking.

Pour in milk, oil and vanilla extract. Mix gently until combined. Avoid overmixing because it can make the cake dense and less tender.

Fold the dry ingredients into the wet mixture. Stir gently using a spatula. Stop mixing when no dry flour remains visible.

Pour batter into the prepared pan. Bake at 350°F (175°C) for 25 minutes. Let the cake cool completely before adding mousse.

Mix gelatin with cold water. Let it sit for five minutes. Heat gently until dissolved. Allow it to cool slightly before use.

Blend mango puree until smooth. Add the dissolved gelatin. Mix well. The puree should be silky and free from lumps.

Beat heavy cream with powdered sugar until soft peaks form. The cream should be fluffy but not too stiff.

Fold the mango mixture into the whipped cream. Mix gently. Keep the mousse light and airy for the best texture.

Place the cooled cake inside a springform pan. Pour the mango mousse over the cake layer. Smooth the top evenly.

Refrigerate for at least four hours. Prepare the topping with mango puree and gelatin. Pour over the mousse and chill again. Garnish with mango slices before serving.