Combine the flour, sugar, salt, and baking powder in a large bowl. In a separate bowl beat the eggs with the ricotta, cottage cheese, milk, vanilla, and lemon zest. Add this mixture to the flour mixture, stirring until moistened. Do not stir any more than necessary to thoroughly combine ingredients. Drop a small amount on a lightly greased griddle or skillet over moderate heat and turn when the edges appear golden brown and dry, and the surface is bubbly.