Combine ricotta cheese and softened cream cheese in a food processor.

Process until the mixture is smooth and creamy.

Add egg yolk, melted butter, sugar, vanilla extract, and salt.

Process until the filling is fluffy.

Divide the cheese mixture evenly among the 12 crepes.

Spread the filling in a thin layer over each crepe.

Roll each crepe tightly around the filling.

Melt 1 teaspoon of butter in a skillet over medium heat.

Fry 3 crepes in the melted butter until heated through and lightly golden brown on each side (1-2 minutes per side).

Repeat with the remaining butter and crepes until all are cooked.