Top: Mix the egg whites with a pinch of salt until you get a firm foam. Add in turn the sugar, the yolks, the oil and the flour mixed with the baking powder, mixing for homogenization according to each ingredient.
Grease the tart pan with oil and line it with flour. Pour the tart composition into the pan and bake the top for approx. 30 minutes in the preheated oven. When the countertop is brown and comes off easily from the edges of the tray, turn off the heat and turn the countertop on a plate, letting it cool.
Cream: Beat the whipped cream first, then add 4 tablespoons of powdered sugar and 250 g of mascarpone. Add the orange essence and the candied citrus pieces, mixing everything for another minute.
Assembly: In the hollow of the countertop we place the grapes, over which we sprinkle 2 tablespoons of powdered sugar, spread the cream, then decorate according to preferences. Having nothing else at hand, I used Dr. Oetker's ornament and quince slices from the compote.