Place a pot of water to boil. Turn on oven to 425°F.
Coat cauliflower florets with half the pesto, roast in the oven until slightly brown, about 15 min.
In a skillet sauté shallot with olive oil for three minutes over medium heat, stir in mushrooms, season with salt and pepper and brown over high heat, about five minutes.
Meanwhile, cook pasta according to package directions. Drain pasta, reserving ½ cup cooking liquid.
Toss pasta with reserved cooking water, remaining pesto, roasted cauliflower, and sautéed mushrooms. Sprinkle cheese and garnish with pomegranate seeds before serving
