In mixer bowl, beat egg yolks; add next three ingredients. Blend until smooth. Combine flour, sugar, salt and 2 tablespoons zest; stir into ricotta mixture. With an electric mixer, beat egg whites until firm peaks form. Gently fold egg whites into batter. Lightly grease griddle; place over medium heat for 1 minute. For each pancake, spoon 1/4 cup batter on griddle in 3-inch circle. Cook pancakes several minutes on each side until golden. Serve immediately or place pancakes on ovenproof dish; cover loosely with foil. Keep warm in 200 F oven.
To Serve: Sprinkle with powdered sugar. Top with remaining lemon zest; garnish with blackberries