Separate the eggs. Whisk the egg yolks until smooth with three-quarters of the ricotta, the almond flour, baking powder, vanilla extract, lemon zest, and a pinch of salt to form a thick batter.
In a grease-free bowl, whip the egg whites with a whisk until soft peaks form, then gently fold them into the batter in two batches. These whipped egg whites are what saves these low-carb pancakes: almond flour lacks gluten to provide structure, and without the air bubbles from the egg whites, you would end up baking flat, dense discs instead of fluffy pancakes.
Melt half of the butter in a frying pan over medium heat. Spoon two tablespoons of batter per pancake into the pan and cook them in batches: two to three minutes per side, flipping them only when the edges look dry and bubbles form on the surface. Almond flour browns faster than regular flour, so keep the heat on the lower side. Cook the remaining pancakes in the rest of the butter.
Heat half of the blueberries with a splash of water for two minutes until they burst, then stir in the remaining blueberries cold.
Stack the pancakes on a plate, top with the remaining ricotta, and spoon the blueberries over them. Dust with the cinnamon.