In a bowl, mix the flour, baking powder, baking soda, vanilla, salt, and cocoa. In another bowl, put the milk, mix in the vinegar, and add the red confectionery color. Mix well and set aside for 5 minutes.
Put the unsalted butter, sunflower oil, and sugar in the mixer bowl and beat with the paddle attachment for 5 minutes until fluffy. Add the eggs one by one, waiting for one to be incorporated before adding the next. Lower the speed of the mixer and add half the amount of flour, the milk mixture, and then the rest of the flour, spoon by spoon.
Place non-stick greaseproof paper on a 26x38cm pan and pour in the mixture. Flatten the surface of the cake with a spatula. Bake in a preheated oven at 150°C (to preserve the color of the cake) using the convection setting for 25 minutes.
Let the cake cool.
For the cream cheese: In the bowl of the mixer, put the butter and powdered sugar and beat with the whisk for 10 minutes, until the butter foams and becomes fluffy. Add the cream cheese and vanilla and beat for another minute. Put the cream in a piping bag.
Using the greaseproof paper, remove the cake from the pan and cut into round pieces with a round or heart-shaped cutter of 8-10 cm diameter. Place a piece of cake on the base of a plate and use the piping bag to make rosettes on top of the cake. Put another piece of cake on top and decorate with extra cream, making rosettes and strawberries.