1. Mix the flour, sugar, baking powder, and salt. Add the oil, milk, and egg. Mix well.
2. Pour into a greased and floured cake pan.
3. Place the apple slices (peeled and cut into about 12 slices!) on top, overlapping them.
4. Bake in the oven for 25 minutes at 350°F (180°C).
5. Prepare the cream: melt the butter and add the sugar, vanilla, and egg.
6. When the cake starts to brown and rise (after 25 minutes), pour the cream over it.
7. Finish baking for another 15 minutes.