Separate the eggs, placing yolks in a large bowl and whites in a clean, dry medium bowl. Zest 1–2 lemons to get 1 tablespoon of zest, then juice half a lemon to get 1 tablespoon of juice.
Add the ricotta, egg yolks, sugar, lemon juice, lemon zest, and vanilla extract to the large bowl and whisk until smooth and creamy, about 1 minute.
Add the flour, baking powder, and salt to the ricotta mixture and stir gently with a rubber spatula until just combined — a few small lumps are fine; do not overmix.
Using a hand mixer on high speed, beat the egg whites until they form stiff, glossy peaks that hold their shape, about 2–3 minutes. Do not over-beat.
Stir one-third of the egg whites into the batter to loosen it, then gently fold in the remaining whites with a rubber spatula until just combined with no large white streaks visible.
Place a non-stick skillet or griddle over medium-low heat and add a small pat of butter, swirling to coat the surface evenly.
Pour about ¼ cup of batter per pancake onto the pan and cook undisturbed for 3–4 minutes until the edges look matte and bubbles form on the surface, then flip and cook 2–3 more minutes until golden brown.
Transfer cooked pancakes to a plate, tent loosely with foil to keep warm, and repeat with remaining batter, adding fresh butter between batches. Serve with powdered sugar, fresh berries, maple syrup, or whipped cream.