1 spaghetti squash, about 2 pounds
4 tablespoons (1/2 stick) unsalted butter
1 1/2 teaspoons salt
1/2 teaspoon freshly ground black pepper
1 tomato, seeded and diced
Preheat oven to 350 degrees F. Cut squash in half lengthwise and remove and discard inner seeds. Coat insides with 1 tablespoon of the butter and sprinkle with 1/2 teaspoon of the salt. Place cut-side down in a roasting pan and add about an inch of boiling water. Cover with aluminum foil and bake 30 minutes. Set aside to cool.
When cool enough to handle, scoop out meat with a spoon, discarding skins. Fluff hot strands with a fork to separate.
Melt remaining 3 tablespoons butter in a large skillet over medium-high heat. Sauté squash with remaining salt and pepper about 5 minutes. Add tomato and cook briefly, to evenly heat. Serve immediately.