1 cup walnuts
1/3 cup lightly packed flat-leaf parsley with thick stems removed
2 cloves garlic, smashed
3 tbsp. grated Parmesan cheese, plus more for serving
1/2 cup olive oil
1/2 tsp. salt
1/4 tsp. fresh-ground black pepper
1 pound fresh or frozen cheese tortellini
1 tablespoon butter
Method of Preparation:
1.In a food processor or blender, pulse the walnuts, parsley, garlic, Parmesan, oil, salt, and pepper to a coarse puree.
2.In a large pot of boiling, salted water, cook the tortellini until just done, about 4 minutes for fresh and 12 minutes for frozen. Reserve 1/2 cup of the pasta water. Drain the tortellini.
3.Toss with 1/4 cup of the reserved pasta water, the walnut pesto, and the butter. If the pasta seems dry, add more of the reserved pasta water. Sprinkle with additional Parmesan.