Lunch: Butternut Squash Polenta

Ingredients

3/4 cup finely chopped onion (1 medium)
5 tablespoons unsalted butter
1 (12-oz) package frozen butternut squash purée (sometimes called winter squash; 1 1/2 cups), thawed
2 1/2 cups water
2 cups whole milk
1 1/4 teaspoons salt
1/4 teaspoon black pepper
3/4 cup instant polenta
1 oz finely grated Parmigiano-Reggiano (1/2 cup)

Instructions

Cook onion in 3 tablespoons butter in a 10-inch heavy skillet over moderate heat, stirring, until very soft, about 8 minutes. Stir in squash and cook, stirring occasionally, 2 minutes.
Bring water, milk, salt, and pepper to a boil in a 4-quart heavy pot. Add polenta in a thin stream, whisking. Cook polenta at a bare simmer, stirring with a long-handled whisk and turning down heat as needed to prevent spattering, 5 minutes.
Stir in squash mixture and cook, stirring, 3 minutes. Remove from heat, then stir in cheese and remaining 2 tablespoons butter. Serve immediately.