In a large bowl, mix ricotta, Parmesan, Pecorino, and mozzarella cheese with egg yolk until combined. Add to a piping bag or resealable plastic bag and snip off the corner.
Add egg yolk and water to a small bowl. Mix with a fork to combine.
- Use a 2-inch ring cutter to cut circles out of the pasta sheets. Brush the edges of each circle with egg wash. Pipe dime-sized portions of the cheese mixture onto each circle.
- To shape the tortellini, fold the circles in half to create a half-moon shape. Pinch the edges shut, then bring the two bottom corners together, pinching tightly to form the tortellini.
- Bring a large pot of salted water to a boil and cook the tortellini for 2-3 minutes, until they are floating and al dente.
Add 1 cup of Carbone Four Cheese Pasta Sauce to a large skillet and bring to a simmer. Add the tortellini and stir to coat with sauce.
Garnish with a generous pinch of OSMO x Carbone Four Cheese Sea Salt and grated Parmesan. Serve and enjoy!