Prepare the Sponge Cake

1. Preheat Oven: Preheat your oven to 350°F (175°C). Line an 8-inch round cake pan with parchment paper.
2. Whisk the Eggs: In a mixing bowl, beat the eggs and sugar together using an electric mixer until light and fluffy, about 5 minutes.
3. Add the Dry Ingredients: Sift the flour, baking powder, and salt together. Gently fold them into the egg mixture with a spatula, making sure not to deflate the batter.
4. Add the Butter: Drizzle the melted butter into the batter and fold gently until just incorporated.
5. Bake: Pour the batter into the prepared pan and smooth the top. Bake for 18–20 minutes, or until a toothpick inserted in the center comes out clean.
6. Cool: Let the cake cool in the pan for 10 minutes before transferring it to a wire rack to cool completely.

Make the Mango Mousse

1. Prepare the Mango Puree: In a blender, combine the chopped mangoes with water and blend until smooth. You should have about 1 cup of mango puree.
2. Prepare the Gelatin: In a small bowl, sprinkle the gelatin over the 1/2 cup of warm water. Let it bloom for 5 minutes, then stir until fully dissolved.
3. Whip the Cream: In a separate bowl, whip the heavy cream until stiff peaks form. Set aside.
4. Combine the Ingredients: Gently heat the mango puree, sugar, and lemon juice in a saucepan until warmed through. Stir in the dissolved gelatin and let it cool slightly.
5. Fold the Whipped Cream: Once the mango mixture has cooled, gently fold in the whipped cream until smooth and fully incorporated. Be careful not to deflate the whipped cream.

Prepare the Mirror Glaze

1. Heat the Glaze Ingredients: In a saucepan, combine water, sugar, and sweetened condensed milk. Bring to a boil and stir to dissolve the sugar.
2. Add the Mango Puree: Stir in the mango puree and bring the mixture to a simmer.
3. Dissolve the Gelatin: Sprinkle the gelatin over the 1/4 cup of cold water, let it bloom, then stir it into the hot glaze mixture until dissolved.
4. Strain the Glaze: Strain the glaze through a fine mesh sieve to ensure it is smooth and free of lumps.
5. Cool the Glaze: Let the glaze cool to around 95°F (35°C) before using it on the entremet. It should be thick but still pourable.

Assemble the Mango Dôme Entremet

1. Prepare the Mold: Lightly grease a dome-shaped mold with non-stick spray or line it with plastic wrap for easy removal.
2. Layer the Mousse: Once the sponge cake has cooled, cut it into circles that fit the base of the mold. Place the sponge cake in the bottom of the mold, pressing it gently to ensure it’s even. Pour the mango mousse on top, filling the mold halfway.
3. Chill the Mousse: Place the filled mold in the refrigerator for at least 2 hours, or until the mousse has fully set.
4. Cover with More Mousse: After the mousse has set, add more mousse to fill the mold. Smooth the top and refrigerate again for an additional 1 hour to firm up.
5. Glaze the Dome: Once the mousse is completely set, carefully pour the mango mirror glaze over the dome, making sure it coats the entire surface. Refrigerate for 30 minutes to let the glaze set.

Finishing Touches

1. Remove from Mold: Gently unmold the entremet from the dome mold. If you used plastic wrap, peel it off carefully.
2. Decorate: Optionally, decorate the entremet with fresh mango slices, edible gold leaf, or any other decorative elements you like.