Wash and dry all produce. Preheat broiler to high. Bring a large pot of salted water to a boil. Halve, peel, and dice onion. Mince garlic. Pick basil leaves from stems and finely chop; discard stems.

Heat a large drizzle of olive oil in a large, tall-sided pan over medium-high heat (use an ovenproof pan if you have one). Add onion and garlic. Cook, tossing, until softened, 4-5 minutes. Season with salt and pepper.

Add beef to pan, breaking up meat into pieces. Cook until browned, 3-4 minutes. Season with salt and pepper. Stir in tomatoes, basil, and 1 cup water. Bring to a simmer, then lower heat slightly and let bubble until saucy, 4-5 minutes. Season with salt and pepper.

Once water is boiling, add tortelloni to pot. Cook, stirring occasionally, until tender, 3-4 minutes. Meanwhile, combine panko, Parmesan, a large drizzle of olive oil, and a pinch of salt and pepper in a small bowl. Once tortelloni are cooked, remove from pot with a slotted spoon and transfer to pan with beef.

Gently stir spinach and sour cream into same pan, allowing spinach to wilt. TIP: If your pan is not ovenproof, transfer everything in pan to a large baking dish at this point.

Sprinkle crust over tortelloni mixture. Place under broiler and broil until browned, about 2 minutes (keep an eye on it—it can burn). Divide between plates and serve.