Cook pasta in a large pot of salted boiling water. Cook until al dente. Reserve two cups of pasta water before draining and setting aside.
Heat butter in a large skillet over medium heat. Add black pepper, pumpkin puree and 1 cup of pasta water. Whisk until combined.
Remove from heat and add in the cooked pasta. Slowly add pecorino Romano cheese, stirring quickly so everything is combined. If the sauce is dry, add reserved pasta water 1 tablespoon at a time to create a sauce.
Top with additional pecorino Romano and serve with crispy sage leaves.