Beat the eggs to foam. Add the sugar and continue beating. Pour in the water and oil. Add the sifted flour and baking powder. Peel, clean and cut the apples into small cubes.
Add them to the mixture and stir well. Pour it into a buttered and floured form. Bake at 356°F (180 °C) for about 40 min. Take it out from the oven, leave it to cool a bit and invert onto a platter.
For the topping, put the sugar and 1 tsp cold water to caramelize. Peel and cut the apples into small cubes, chop the walnuts coarsely. After the sugar gains a caramel color, add the apples and after 3-4 min. add the heated cream. Stir until it dissolves and thickens a little.
Remove from the stove and leave it to cool. Distribute the caramelized apples onto the cake, sprinkle with walnuts and pour on the caramel sauce.