1 tube prepared polenta, sliced into 1-centimeter-thick rounds
2 tablespoons extra-virgin olive oil, plus more for brushing
1/4 cup (1/2 stick) unsalted butter
900 grams assorted wild mushrooms (such as oyster, cremini, and/or stemmed shiitake), cut into thick slices
2 shallots, thinly sliced
1/4 cup Sherry
Kosher salt and fresh ground pepper
1 cup coarsely grated Fontina cheese
Fresh parsley, chopped for garnish
Preheat oven to 450°F. Brush both sides of polenta slices very lightly with oil and arrange on a parchment lined baking sheet. Roast polenta until lightly golden brown and warmed through, about 25 minutes.
Meanwhile, melt butter with remaining two tablespoons of oil in large, deep skillet over medium-high heat. Add mushrooms and cook, stirring often, until tender and browned, about 12 minutes. Add the shallots and Sherry and season well with salt and pepper. Continue cooking until tender, about five minutes longer.
Divide mushroom mixture over the polenta rounds. Top with grated cheese. Continue to roast until cheese is melted, about five minutes.
Arrange polenta bites on a platter, garnish with parsley and serve. Bon appetit!