Ingredients

1 medium sweet yellow onion
2 tablespoons extra-virgin olive oil
2 tablespoons butter
Salt
2 pounds fresh tomatoes
4 dried bay leaves (or fresh, if available)
Freshly ground black pepper
1 pound spaghetti (penne or maccheroni are also good)
⅓ cup freshly grated Parmigiano-Reggiano




Steps

1. Fill a pot for the pasta with about 6 quarts of water, place over high heat, and bring to a boil.

2. Peel the onion and slice thinly crosswise. 
    Put it with the olive oil and butter in a 12-inch skillet. Place over medium-high heat, season lightly      with salt, and saute until the onion turns a rich golden color, 6 to 8 minutes.

3. While the onion is sauteing, peel the tomatoes and coarsely chop them.

4. When the onion is ready, add the tomatoes and bay leaves, season with salt and pepper, and cook        until the liquid the tomatoes release has almost completely evaporated, 10 to 12 minutes. 
    Remove from the heat.

5. After the tomatoes have been cooking for about 8 minutes, add about 2 tablespoons salt to the              boiling pasta water, add the spaghetti, and stir until all the strands are submerged. 
    Cook until aldente.

6. When the pasta is done, drain well, toss with the sauce and Parmigiano-Reggiano