Heat the oil with garlic in a large frying pan and cook until fragarant, about 1 minute. Add lemon slices and sauté for 3-4 minutes until lightly golden on both sides.
In the meantime heat 7 quarts of water to boiling and add 2 tablespoons of salt. Add broccoli florets and cook 3-4 minutes. Drain broccoli florets with a slotted spoon keeping the water and transfer to the pan. Cook on high-heat for 3-4 minutes until well roasted. Season with salt and pepper to taste.
In the same water you used to cook broccoli, cook Tortelloni according to package instructions and drain, reserving a ladleful of the pasta cooking water. Add the pasta to the pan and stir gently, adding some of the pasta water if you need to loosen the sauce.
Divide among plates. Sprinkle with grated pecorino and more pepper and serve.