Serves 3-4 entree; 6-8 appetizer          Time: 30 minutes including prep

1 lb peeled butternut squash pieces cut into 1" rough dice
1 small onion, diced
1/2 stick (1/4 cup) unsalted butter
1 tablespoon finely chopped fresh sage (or a small bunch, unchopped, see recipe for details)
1 1/2 cups water
3/4 teaspoon salt
1/2 teaspoon black pepper
2 oz finely grated Parmigiano-Reggiano (1 cup) plus additional for serving
1 lb penne rigate or rotini or whatever pasta shape you like

1. Heat butter in a 5- to 6-quart heavy pot over moderately high heat until foam subsides, then add sage and cook until fragrant, about 15 seconds. (Note: I just added my bundle of sage to the butter intact and removed it before puréeing the sauce.) Add cubed squash, diced onion, water, salt, and pepper and simmer, uncovered, stirring occasionally, until squash is very tender and water has reduced considerably, about 8 to 10 minutes.

2. If you wish, stir in Parmigiano-Reggiano. (Note: I did not do this — the mixture tasted wonderful without any cheese, so I just served the cheese on top of the pasta.) If you didn’t chop up the sage, extract what is left of the bundle you added to the pot — I didn’t pull out every sage leaf, just the bigger leaves still attached to the stem. If you have an immersion blender, purée mixture right in pot. If you don’t, transfer mixture to a food processor or blender. Remove squash mixture from heat.

3. While squash mixture simmers, cook pasta in a 6- to 8-quart pot of boiling salted water with a large pinch of kosher salt until al dente. Reserve 1 cup pasta cooking water, then drain pasta in a colander.

4. Place pasta in a serving bowl. Toss with enough butternut-sage sauce to coat nicely. If necessary, add a little bit of the reserved cooking water to thin it out. Serve pasta with additional cheese on the side.

Note: If you have extra sauce, store it in the fridge for a later date. The sauce thickens as it sits, so on subsequent uses, it will most likely be necessary to use the reserved cooking liquid to thin out.