Preheat the oven to 350 F (180 C).
Line 8 muffin tin holes with paper cases.

In a bowl, mix the ricotta, yogurt, milk, melted butter, lemon zest, and lemon juice. Set aside.

In another bowl, mix the flour, baking powder, sugar, and vanilla sugar.

Combine the wet ingredients with the dry ingredients, just enough to moisten.
Divide the mixture among the prepared muffin cases.

Bake for 20 to 25 minutes, or until a toothpick inserted into the center comes out clean.
Remove from the oven and let cool on a wire rack.