Wash the lemon and grate the peel. Halve lemon, squeeze juice. Sieve flour and baking powder into a mixing bowl. Add sugar, lemon zest, eggs, oil and Prosecco and mix well. Drain the mango, cut into small cubes and fold into the dough.
Line the fat pan of the oven (32 x 39 cm) with baking paper. Put the dough on top and smooth it down. Bake in the preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: level 2) for about 20 minutes. Take the cake out of the oven, pull it off the baking tray with the baking paper and let it cool down on a cake rack. Sift icing sugar into a bowl. Mix icing sugar and lemon juice. Remove 6 tablespoons of icing, put 2 tablespoons in each small bowl and colour them light green, pink and lilac. Colour the remaining icing light yellow. Pour coloured glazes into 1 piping bag each and cut off a small corner. Cut out large (10 x 8 cm) and small (5 x 7 cm) Easter eggs from the cake.
Remove 6 tablespoons of icing, put 2 tablespoons in each small bowl and colour them light green, pink and lilac. Colour the remaining icing light yellow. Pour coloured glazes into 1 piping bag each and cut off a small corner. Cut out large (10 x 8 cm) and small (5 x 7 cm) Easter eggs from the cake. Cover each egg with yellow icing and draw longitudinal stripes with pink, lilac and green icing. With a toothpick, pull through the longitudinal stripes alternately from right and left to get the pattern. Finally draw a coloured border around the eggs