Separate 4 large eggs, placing the whites in the bowl of stand mixer fitted with the whisk attachment and the yolks in a large bowl. (Alternatively, you can place the whites in a medium bowl if using an electric hand mixer or whisking by hand with a sturdy whisk.)

Finely grate the zest 1 medium lemon onto the egg yolks, then squeeze the juice from the lemon into the bowl (about 1 tablespoon zest and 3 tablespoons juice). Add 1 cup whole-milk ricotta cheese and 1/2 cup whole or 2% milk, and whisk to combine. Add 1 cup all-purpose flour, 1 tablespoon granulated sugar, 1 teaspoon baking powder, and 1/4 teaspoon kosher salt, and whisk until just combined; do not overmix.

Beat the egg whites on medium-high speed until stiff peaks form, 2 to 3 minutes. (Alternatively, beat with an electric hand mixer or sturdy whisk.) Stir 1/3 of the beaten egg whites into the egg yolk batter with a rubber spatula to lighten it. Then gently fold the remaining egg whites in until just combined; do not overmix.

Heat a large cast iron or nonstick skillet or griddle over medium heat. Add 1 teaspoon unsalted butter to the pan and swirl to coat. Drop the batter into the pan in 1/4 cup portions, 3 at a time. If needed, use the bottom of the measuring cup or the spatula to gently spread out each portion into rough 4-inch rounds. Cook until bubbles appear on the surface, the edges begin to look dry, and the bottoms are golden-brown, 2 to 3 minutes. Flip the pancakes and cook until the other side is golden-brown, 2 to 3 minutes more.

Transfer the pancakes to a warm oven or plate. Repeat cooking the remaining batter, using 1 teaspoon butter for each batch and wiping out the skillet between batches, as needed. Serve the pancakes immediately, with topping of choice.