Prepare the Sponge Cake:
Preheat your oven to 350°F (175°C). Grease and flour a round cake pan.
In a mixing bowl, whisk together flour, baking powder, and salt.
In another bowl, beat the eggs and sugar until light and fluffy.
Carefully add in the warm milk, vegetable oil, and vanilla, mixing until well combined.
Gradually fold the dry ingredients into the wet ingredients until just incorporated.
Pour the batter into the prepared pan and bake for 25-30 minutes. Let cool completely.
Make the Strawberry Mousse:
Blend the fresh strawberries, sugar, and lemon juice in a bowl.
In a small bowl, combine gelatin with cold water. Let it sit for a few minutes, then gently heat it to dissolve. Add it to the strawberry mixture.
Whip the heavy cream to soft peaks and carefully fold it into the strawberry mixture. Chill until slightly set.
Prepare the Strawberry Jelly Topping:
Blend the strawberries with sugar in a bowl.
Dissolve the gelatin in cold water and mix it into the strawberry puree.
Assemble the Cake:
Once the sponge cake is cooled, layer the strawberry mousse on top, and add the jelly topping. Chill again before serving.