Prosciutto Ravioli

From Everyday Pasta - Giada DeLaurentiis

1 (15oz) container whole-milk ricotta cheese
1 (10oz) package frozen chopped spinach, thawed, squeezed dry
4oz sliced prosciutto, chopped
2 large egg yolks
3/4 tsp salt
1/2 tsp freshly ground black pepper
48 square wonton wrappers
1/2 C unsalted butter
1 1/2 tsp dried oregano
Freshly grated Pecorino cheese

Whisk the ricotta, spinach, prosciutto, egg yolks, salt, and pepper in a medium bowl to blend.
Place 1 tablespoon of the ricotta filling in the center of a wonton wrapper. Brush the edge of the wrapper lightly with water. Fold the wrapper in half point to point, enclosing the filling completely and forming a triangle. Pinch the edges to seal. Transfer the ravioli to a baking sheet. Repeat with the remaining filling and wrappers. (Can be prepared up to 2 hours ahead; cover and refrigerate).
Bring a large pot of salted water to a boil. Working in batches, cook the ravioli until just tender, stirring occasionally, about 4 minutes per batch. Transfer the ravioli to a large shallow bowl.
Melt the butter in a small, heavy skillet over medium heat. Add the oregano and stir for 1 minute. Season to taste with salt and pepper. Pour the oregano butter over the ravioli and toss gently to coat. Sprinkle with the Pecorino cheese and serve.