Preheat the oven to 100 degrees celsius.

In a small bowl, whisk the flour, baking powder and salt. In a large bowl, whisk the egg yolks with the milk, ricotta, sugar and vanilla. Add the dry ingredients and whisk until the batter is smooth.

In a large bowl, using an electric mixer, beat the egg whites at medium speed until frothy. Beat at high speed until soft peaks form. Fold in 1/3 of the egg whites into the batter to temper it, then fold in the remaining egg whites until no streaks remain.

Preheat your frying pan on low-medium heat, then lightly butter it.

For each pancake, ladle about 1/4 cup of the batter for each pancake. You may be able to put more than one pancake in the pan at a time but make sure you leave enough space between them. Sprinkle each pancake with a few blueberries and press lightly. Cook until the bottoms are golden and the pancakes are just beginning to set, about 1 to 2 minutes.

Flip the pancakes and cook until golden on the bottom and cooked through, about 1 minute longer. Transfer the pancakes to a plate and keep them warm in the oven while you make the rest.

Serve warm.