tomato and cream sauce

3 tablespoons unsalted butter
1 medium onion , minced
2 pounds ripe tomatoes , cored, peeled, seeded, and cut into 1/2-inch pieces
1/2 cup heavy cream
2 tablespoons chopped fresh basil
Table salt
1 pound pasta (see note)
Instructions

1.

1. Heat butter in medium skillet over medium heat; sauté onion until golden, about 5 minutes. Stir in tomatoes; increase heat to medium-high and cook until liquid given off by tomatoes evaporates and tomato pieces lose their shape to form a chunky sauce, about 10 minutes. Add cream to sauce; simmer until cream thickens slightly, 2 to 3 minutes longer. Stir in basil and salt to taste; cover to keep warm.
2.

2. Meanwhile, bring 4 quarts water to boil in large pot or soup kettle. Add 1 tablespoon salt and pasta. Cook until pasta is al dente (refer to package directions; cooking times vary with different shapes). Reserve 1/4 cup cooking water; drain pasta and transfer back to cooking pot. Mix in reserved cooking water, and sauce; toss well to combine. Serve immediately.