In a large skillet, heat 2 tablespoons of the oil. Add the garlic and cook for 30 seconds. Add the broccoli, 1/2 cup of water and the butter, cover and cook over moderately low heat until tender, 10 minutes. Let cool. Coarsely puree the broccoli in a food processor; transfer to a bowl. Stir in the ricotta and 1/4 cup of the pecorino and season with salt.