Egg Yolk Ravioli (Raviolo al Uovo)

Name: Egg Yolk Ravioli (Raviolo al Uovo)
Prep time: 1 h 10 min
Cook time: 10 min
Total time: 1 h 20 min
Cuisine: Italian
Ingredients: 1 cup whole milk ricotta cheese (homemade or store-bought | strained if excessively watery | see notes); 1 1/4 cup parmigiano-reggiano cheese (finely grated); 1 teaspoon freshly ground black pepper; Salt (to taste); 1/2 batch homemade pasta dough; 00 flour or semolina flour (for dusting); 8 large eggs; 1 1/2 sticks unsalted butter; 10 sage leaves; Salt and black pepper (to taste); finely grated parmigiano-reggiano cheese (for topping)