Batter: Mix together the egg yolks, sugar, milk, and vanilla. In a separate bowl, mix the flour, baking powder and salt. Stir the dry ingredients into the yolks mixture just until no large lumps remain.

Beat Egg Whites: In another large bowl, beat the egg whites with a hand mixer until stiff peaks. Gently fold the egg whites into the pancake batter, just until incorporated.

Cook: Lightly grease a large skillet with butter or cooking spray, over LOW heat. Grease 3.5-inch (9 cm) metal ring molds* well with butter (as many as can fit at a time in your skillet) and set them in the middle of the pan over LOW heat. Fill the molds 2/3 with batter, then cover the pan with a lid and cook for about 10 minutes, until the center of the pancakes are only slightly jiggly.

Flip: Release the pancakes from the bottom of the pan with a spatula, then carefully flip them over, making sure not to spill any batter inside. (I like to slide a spatula under the pancake and place another spatula on the top of the pancake ring mold, flip, then place it back in the pan and slide the spatula out.) Cover and cook for another 5 minutes or so, until cooked through, but soft.

Serve with butter, syrup, and berries.