Preheat oven to 425°F. Combine tomatoes (crushing them with your hands), garlic, butter, and ½ teaspoon red pepper flakes in a 13x9" baking dish; season with salt and black pepper. Roast, tossing halfway through, until garlic is very soft and mixture is jammy, 35–40 minutes. Using the back of a fork, mash to break up garlic and tomatoes.
Meanwhile, cook pasta until al dente. Drain, reserving ½ cup pasta cooking liquid.
Return pasta to pot and add tomato sauce and pasta cooking liquid. Cook over medium-high heat, tossing until sauce coats pasta, about 3 minutes. Serve topped with Parmesan, red pepper flakes and toasted breadcrumbs.
To make the breadcrumbs: Place a large non-stick skillet over medium heat with the olive oil and butter. Add the bread and sauté for 3-5 minutes until it starts to turn golden brown. Add the garlic and salt and continue to sauté for about 1-2 more minutes until fragrant and toasted. Remove from heat and transfer to a paper towel lined plate to drain any excess oil. Use as needed.
