Lemon Blueberry Pancakes

Whisk dry ingredients together: In a large bowl, whisk the flour, sugar, baking powder, and salt until well-mixed and lump-free.
Combine wet ingredients: In a separate bowl, whisk together egg yolks, buttermilk, melted (and cooled) butter, lemon zest, lemon juice, and vanilla extract until smooth.
Whip egg whites: In a third bowl, beat egg whites with an electric mixer or hand whisk until stiff peaks form and are glossy.
Bring batter together: Pour the wet mixture into the dry ingredients and gently stir until just combined. Some lumps are okay.
Gently fold whipped egg whites into the batter, being careful not to deflate them. The batter should look aerated and a little thick.
Let the batter rest for 5 minutes to allow the bubbles to settle and the flour to hydrate.
Heat the pan: Preheat a griddle or large non-stick skillet over medium heat and lightly grease with butter or oil.
Scoop 1/4 cup of batter onto the hot griddle for each pancake. Gently scatter a few blueberries over each pancake. Do not mix berries into batter beforehand.
Cook until bubbles rise to the surface and the edges look set, 1–2 minutes. Flip and cook until the other side is golden brown, about 1–2 minutes more.
Transfer pancakes to a wire rack or warm oven as you finish the batch. Serve hot with butter, maple syrup, extra blueberries, and more lemon zest, if desired.