• Get ready. Preheat your oven to 450°F.
• Prep the tomatoes and vegetables. To a large sheet pan (or two medium ones), add the tomatoes, onions, garlic, and carrots. Sprinkle on the Italian seasoning, red pepper flakes, and a big dash of salt and pepper. Drizzle a generous amount of olive oil (about 3 tablespoons) all over the vegetables and toss to coat. Spread the vegetables well so that they are in one single layer and the tomatoes are cut side down.
• Roast. Cook on the middle rack of the heated oven for about 35 to 45 minutes, or until the tomatoes have fully collapsed and the veggies have gained some color and charred in some parts.
• Remove from the heat and set aside to cool briefly. If you like, use a pair of tongs to remove the tomato skins and discard (sometimes I just leave the skin on for texture when I want a chunkier sauce).
• Blend. Transfer the tomatoes and their juices and the vegetables to the large bowl of a food processor fitted with a blade. For a smooth and silky sauce, close the lid and blend until you reach the desired consistency. If you want a rustic, chunkier tomato sauce, pulse until the tomatoes and vegetables are broken up to your desired consistency.
• Use or or store. Use immediately, or let cool fully before storing.

If You're Serving with Pasta

• Make the pasta. Bring a pot of water to a boil and season well with kosher salt. Cook according to package instructions, reserving a 1/2 cup of pasta water before draining.
• Mix. Add a splash of pasta water to the blender and blend briefly to incorporate. Return the pasta sauce to the pan and add the cooked, drained pasta. Mix well with a wooden spoon to coat the pasta well, adding more pasta water as needed to create a thick and silky sauce coating your pasta.
• Serve. Garnish with fresh basil and parmesan cheese. Enjoy!