Cheesy Polenta & Mushroom Pizza

Line a baking sheet with parchment paper. Cook the polenta according to package directions. Remove from heat and stir in the Parmesan, 1/4 cup Gruyère and 1/4 tsp each salt and pepper. Scrape the polenta onto the prepared baking sheet and spread out to form a 3/4-in.-thick oval. Heat broiler. Heat 2 Tbsp of the oil in a large skillet over medium high heat. Add half the mushrooms and cook, tossing often, until golden brown and just tender, 4 to 5 minutes; transfer to a plate. Cook the remaining mushrooms with the remaining Tbsp oil. Return the first batch of mushrooms to the skillet and toss with the shallot, thyme, 1/2 tsp salt and 1/4 tsp pepper. Scatter the mushroom mixture over the polenta and sprinkle with the remaining 1/4 cup Gruyère. Broil until the cheese begins to brown, about 3 minutes. Serve with a salad, if desired.