Tomatoes, pesto, and parmesan cheese are all it takes. Garten roasts the tomatoes to upgrade their flavor, caramelizing their natural sugars and concentrating their umami richness.
Cut the tomatoes into half-inch thick rounds and pat them dry. Drizzle the slices with olive oil and plenty of salt and pepper before roasting them for 10 minutes at 425 degrees.
Slather the tomatoes with pesto and parmesan and roast again for 10 minutes. This will melt the cheese and continue developing the tomato slices' sweet umami notes.