Preheat the oven to 400°F (207°C). Rinse the tomatoes and slice them in half. Toss them gently with olive oil, then season with salt and pepper. Arrange the tomatoes in a baking dish and top with Parmesan cheese. Roast for about 15-20 minutes, or until the Parmesan cheese is melted and slightly browned.: The moment you set the oven to 400°F you begin the transformation. You will smell the faint electrical hum in my oven and the air warms quickly, setting the stage for caramelization. Getting the oven fully hot ensures the Parmesan cheese melts and browns, rather than steaming the tomatoes. If you skip a full preheat you may end up with soggier fruit and pale cheese, so wait until the oven reaches temperature.
Remove from the oven and serve immediately.: Freshly rinsed tomatoes hold a bright, cleancolored flesh and their skins tense slightly when patted dry. Slicing them in half exposes more surface area for roasting and for the Parmesan cheese to cling to. Use a sharp knife so the slices are clean and even, because ragged cuts can leak juices during roasting and cause uneven texture.
Toss them gently with olive oil: When the tomato halves glisten with a thin film of olive oil they take on a silkier mouthfeel as they roast. Oil helps heat distribute and concentrates flavor on the exposed flesh, and it supports a more even browning of the cheese. Avoid over tossing, which can bruise the tomato flesh and release excess juices.
Season with salt and pepper: A pinch of salt and a grind of ground black pepper amplify the tomato's natural sweetness and lend a savory backbone. Salt draws out water, intensifying flavor, while pepper adds a subtle heat. Add a conservative amount at first since roasting sharpens these seasonings, and adjust after baking if needed.
Arrange the tomatoes in a baking dish and top with Parmesan cheese: Place the halves cut side up so they catch the Parmesan cheese and brown on top. The visual cue to watch for is the cheese melting into glossy pockets and beginning to turn golden at the edges. If you crowd the dish the tomatoes will steam instead of roast, so give them breathing room for proper caramelization.
Roast for about 15 to 20 minutes or until the Parmesan cheese is melted and slightly browned: The kitchen will fill with a toasty, savory aroma as sugars in the tomatoes concentrate and the Parmesan cheese crisps. Look for bubbling cheese with golden flecks and slightly wrinkled skins, which signal readiness. Opening the oven too often drops the temperature and can lengthen the cooking time, so check visually through the door rather than repeatedly pulling the tray out.
Remove from the oven and serve immediately: Hot roasted tomatoes are at their peak as soon as they come out, with molten cheese and concentrated juices. Serve right away so you enjoy the contrast of warm cheese and tender tomato. Letting them sit too long results in more liquid pooling and a loss of crispness on the cheese.