- Prepare a 18-20cm (7.09-7.87 inch) baking tin: line it with parchment, or grease with butter and sprinkle with flour.
- Sift the flour, baking soda and salt.
- Beat soft butter with sugar until fluffy, for at least 5-7 minutes.
- Pour in vegetable oil, and beat again.
- Add the egg and vanilla extract, and beat.
- Add half of the buttermilk.
- Then add all the dry ingredients in batches while continuing to beat.
- At the end, mix in the rest of the buttermilk with a spatula.
- Bake in preheated oven at 356F (180C) for about 15-20 minutes, checking readiness with a toothpick. It should come out dry from the center.
- Cool on a wire rack.
Cream cheese mousse
- Soak gelatin in water, and leave to swell according to the instructions.
- Boil the strawberry puree for about 5-7 minutes until thick; remove from the heat, combine with swollen gelatin and mix thoroughly.
- Whip the cream cheese with cream and powdered sugar until fluffy and combined.
- Add a few tablespoons of the cheese mixture to the strawberry puree with gelatin, and mix.
- Combine all the filling, and beat.
- Put the cooled sponge biscuit into a detachable tin or a ring. If desired, cover the edges with an acetate film. Cover the bottom tightly with foil.
- Lay strawberry halves around the edge, lay out the mousse, and leave in the fridge until solidified.