I have been making it the last few years and constantly tweaking the recipe. I think this is the final keeper. I adapted it from one of my favorite chef's, The Barefoot Contessa! I think roasting the tomatoes is the key!
•3 pounds ripe plum tomatoes, cut in half lengthwise (I used ripe Roma's)
•1/4 cup plus 2 tablespoons good olive oil
•1 tablespoon kosher salt
•1 1/2 teaspoons freshly ground black pepper
•2 cups chopped yellow onions (2 onions)
•6 garlic cloves, minced
•2 tablespoons unsalted butter
•1/4 teaspoon crushed red pepper flakes
•1 (28-ounce) canned plum tomatoes, with their juice
•4 cups fresh basil leaves, cut into a chiffanade (I used only 2 cups)
•1 teaspoon fresh thyme leaves
•1 quart chicken stock or water (use stock)
Preheat the oven to 400 degrees F. Toss together the tomatoes, 1/4 cup olive oil, salt, and pepper. Spread the tomatoes in 1 layer on a baking sheet and roast for 45 minutes.
In an 8-quart stockpot over medium heat, saute the onions and garlic with 2 tablespoons of olive oil, the butter, and red pepper flakes for 10 minutes, until the onions start to brown.