Polenta Torta

Bring 7 1/2 cups water to a boil in a large pot over high heat.

Add 1 1/2 tbsp. salt and the bay leaves.

Whisking constantly, gradually add polenta. Reduce heat to medium and cook, whisking often, until mixture begins to thicken, then adjust heat to maintain a gentle bubble. Cook, stirring occasionally with a sturdy rubber spatula and scraping pot, until polenta is thick and creamy and grains are softened, 30 to 45 minutes. If it becomes too stiff to stir easily, add a little boiling water.

Melt 3 tbsp. butter in a medium nonstick frying pan over medium-low heat.

Add onions and cook, stirring often, until soft and pale golden, about 20 minutes.

Preheat oven to 37

Remove bay leaves from polenta. Stir in onions and season with salt to taste.

Butter a 13- by 9- by 2-in. baking dish generously.

Pour one-third of polenta into dish, spreading evenly. Top with half of truffled cheese.

Add another one-third of polenta, then remaining truffled cheese. Dollop remaining polenta on top and spread evenly.

Sprinkle with parmesan and dot with remaining 1 tbsp. butter.

Bake torta until medium brown, bubbling on the edges, and hot to the touch, 40 to 45 minutes.

Let cool, then chill until cold, at least 2 hours and up to 1 day.

Cut torta into small rectangles (about 1 1/2 by 2 in.) and transfer to a baking sheet. Broil 4 inches from heat until browned and crisp, about 5 minutes.

Make ahead: Through step Cover with plastic wrap and chill several hours or overnight.