Step 1: Preheat your oven to 400°F (200°C) and prepare a large rimmed baking sheet.
Step 2: Slice the larger heirloom tomatoes into wedges and halve the smaller ones. Place them on the baking sheet with the smashed garlic cloves.
Step 3: Drizzle with olive oil and balsamic vinegar, then sprinkle with salt and red pepper flakes. Toss to coat evenly.
Step 4: Roast for 25-30 minutes until the tomatoes have softened and released their juices, and some edges are slightly charred.
Step 5: While roasting, cook the pasta in a large pot of salted boiling water until al dente. Reserve 1/2 cup of pasta water before draining.
Step 6: Combine the cooked pasta with the roasted tomatoes and all the tray juices in the pasta pot. Toss over low heat, adding reserved water as needed.
Step 7: Stir in the fresh basil and serve immediately with a sprinkle of Parmesan cheese.