Wash and dry all produce. Preheat broiler to high (or oven to 500 degrees). Bring a large pot of salted water to a boil. Halve tomatoes lengthwise. Cut mozzarella into small cubes.

In a small bowl, mix together mozzarella and panko.

Heat a large drizzle of oil in a large pan over medium-high heat (use an ovenproof pan if you have one). Add tomatoes and cook, tossing, until they start to burst, 3-4 minutes. Remove pan from heat and add spinach. Set aside.

Once water is boiling, add ravioli to pot. Cook until al dente, 4-5 minutes. Carefully scoop out and reserve 1/4 cup ravioli cooking water, then drain.

Transfer ravioli to pan with tomatoes and spinach. Return pan to medium heat. Add pesto, reserved ravioli cooking water, and sour cream. Stir gently until spinach wilts and a creamy sauce forms, about 2 minutes. Season with salt and pepper. TIP: If your pan isn't ovenproof, transfer mixture to a medium baking dish at this point

Sprinkle ravioli with panko crust mixture. Broil (or bake) until panko is golden brown and cheese melts, 3-5 minutes. Divide between plates and serve.