Bring a large pot of heavily salted water to boil. Cut the broccoli into small pieces, including the stem, and cook in the water for 5 minutes.
While the broccoli is cooking, bring the olive oil to heat in a large fry pan. Add the garlic to the pan and cook for 3 minutes on a low heat or until fragrant and translucent. Transfer the broccoli to the pan with 1 cup of broccoli water and cook for 10 minutes on a low - medium heat. Reserve the broccoli water in the pot.
While the broccoli continues to cook, cook your pasta. Add San Remo penne pasta to the pot of broccoli water. Drain your pasta 2 minutes before the suggested cooking time (10 minutes) as it will continue to cook when it’s stirred through the sauce. Reserve 1/2 - 1 cup of pasta water.
With a potato masher, mash the softened broccoli to a texture of your liking. Add the pasta, pecorino romano and salt and pepper to the pan with the broccoli. Slowly incorporate the pasta water and stir through on a low heat until you have a smooth and silky texture. Take off the heat and finish off with a squeeze of lemon and sprinkling of chili flakes.