Wash and peel the apples, cut them into quarters, remove the part with the core from each one and then slice them fairly thinly, Using an electric whisk, beat the eggs with half of the sugar, the yoghurt and the softened butter (taken out of the fridge half an hour beforehand). Gradually incorporate the flour sifted together with the baking powder, and when you have obtained a smooth mixture, divide it into two equal parts. Grease the baking tin with butter and pour one part of the cake mixture into it. Cover it with the slices of apple and the remaining sugar Distribute the second part of the cake mixture on top, so that it completely covers the slices of apple. Sprinkle the chopped almonds over the surface. Bake in a preheated oven, at 180 °C, for 30 minutes (if the cake starts to go too brown, after 15 minutes cover it with kitchen foil). Take the apple cake out of the oven, leave it to cool down and then sprinkle it with icing sugar.