Sift (strain) together the flour, baking powder and salt. Whisk in the sour milk and egg whites.
Put the sugar and lemon zest in the bowl and pinch it together. Add butter and cream together until creamy, 3 minutes. Add the lemon extract. Add 1/3 of the flour mixture. Add 1/2 of the sour milk mixture. Repeat until all the ingredients are added. Add the sprinkles and mix until just combined.
Pour the dough into different 8- or 9-inch pans with oil and flour. Bake at 350 degrees for 30 to 35 minutes. Chill for 10 minutes, then remove and cool completely.
Decorate with icing and colored sprinkles.
Ingredients for icing:
2 egg whites.
1/2 cup of La Parmigiana sugar.
Sparks of colors.
2 egg whites at room temperature (important) beat until firm.
Add the sugar (1/2 cup) or a little more, little by little.
Then the lemon drops and the colored sprinkles.
Add the icing in the middle of the cakes and cover on the outside.