2 Tbsp. extra-virgin olive oil (EVOO), plus more for drizzling
2 Tbsp. unsalted butter
1/2 pound bulk sweet Italian sausage
1 portobello mushroom, stem removed
1 small yellow onion, chopped
4 large garlic cloves, chopped
2 fresh rosemary sprigs, leaves stripped and finely chopped
1/2 teaspoon crushed red pepper flakes
Salt and finely ground black pepper
1/2 cup chicken stock or broth
Zest and juice of 1 lemon
2 cups ricotta cheese
1/2 cup grated Parmigiano-Reggiano
1/2 cup plain breadcrumbs
1 24-ounce tube prepared polenta, plain or flavored, cut into 21 disks about 1/4-inch thick
1 cup shredded mozzarella
Preheat the oven to 450°.
Preheat a large skillet over medium-high heat with the 2 tablespoons of EVOO (twice around the pan) and the butter. Once the butter is melted, add the sausage, breaking it up with the back of a wooden spoon. While the sausage is starting to brown, cut the portobello mushroom in half and then thinly slice and add to the sausage. Chop and add to the pan as you go the onions, garlic and rosemary. Season the sausage and mushrooms with the red pepper flakes, salt, and pepper. Once everything is in the pan, the sausage is lightly browned, and the mushrooms and onions have wilted, add the chicken stock and lemon juice. Continue to cook over high heat until the liquids have evaporated, about 2 to 3 minutes.
While the sausage and mushrooms are cooking down in the liquid, in a bowl, combine the ricotta cheese with the egg, lemon zest, Parmigiano, and the breadcrumbs.
Brush an 8-inch spring form pan or an 8" x 8" baking dish with a little EVOO and place 7 disks of the polenta on the bottom of the dish. If they overlap a little that's fine; it will vary depending on what kind of dish you are using. Divide the sausage and mushroom mixture into 3 even portions. Do the same with ricotta mixture.
Using the back of a spoon, spread one third of the ricotta mixture on top of the polenta. Don't make yourself crazy doing this—just mush it out over the polenta. Top the ricotta with a third of the sausage and mushrooms. Repeat the layers two more times, starting with the polenta and finishing with a sausage and mushroom layer. Sprinkle the top with the mozzarella. Cover the baking dish with aluminum foil, transfer to the oven, and bake for 15 to 18 minutes. To make sure it is cooked through, insert a knife into the center of the dish, wait a few seconds, and then remove it. Touch the knife with your fingertips and if it is hot, the lasagna is done. Remove from the spring form (or cut loose from the baking dish) and serve.
Sweet and Savory Polenta "Lasagna"
1/2 cup golden raisins
1/2 cup pine nuts
Prepare just as for the master recipe, adding the raisins and pine nuts at the same time you add the chicken stock and lemon juice to the sausage and onions.
Sausage, Mushroom, and Olive Polenta "Lasagna"
4 rounded tablespoons store-bought black or green olive tapenade.
Prepare just as for the master recipe, adding the tapenade to the ricotta cheese along with the egg, lemon zest, Parmigiano, and breadcrumbs.
Sausage, Mushroom, and Pesto "Lasagna"
4 tablespoons store-bought good-quality pesto
Prepare just as for the master recipe, adding the pesto to the ricotta cheese along with the egg, lemon zest, Parmigiano, and breadcrumbs.