2 tablespoons olive oil
1 pound sweet Italian sausage, casings removed
2 onions, thinly sliced
1 large red bell pepper, cored, seeded, and cut into 1/3-inch strips
1 large green bell pepper, cored, seeded, and cut into 1/3-inch strips
Coarse salt
2 garlic cloves, minced
1 teaspoon dried oregano, preferably Mexican
Pinch of crushed red pepper
1 cup canned tomatoes, with their juices
1 3/4 pounds all-purpose or russet potatoes
1/4 cup all-purpose flour
1/2 cup freshly grated Pecorino or Parmesan cheese
Freshly ground black pepper
2 cups half-and-half

Heat the oil in a large heavy skillet over medium heat until shimmering. Crumble in the sausage and cook, stirring and breaking up the meat with the side of your spoon, until it loses its pink color. Spoon off all but about a tablespoon of the fat.

Add the onions and bell peppers, season with salt, and cook, stirring frequently, until the vegetables are soft, about 10 minutes. Add a tablespoon or two of water if the pan dries out and the vegetables start to stick. Add the garlic and cook for about 1 minute, until fragrant. Then add the oregano, crushed red pepper and tomatoes. Stir and break up the tomatoes with the side of your spoon and cook until very thick, about 7 minutes. Remove from the heat.

Preheat the oven to 350 degrees F. Grease a 3-quart casserole.

Peel the potatoes and cut them into 1/8-inch-thick slices. Combine the flour with 1/4 cup of the cheese.

Place one-third of the potatoes in a layer in the casserole. Season with salt and pepper and sprinkle with half the flour mix. Spoon on half the sausage and peppers. Again, layer potatoes, with salt and pepper, the rest of the flour mixture, and the rest of the sausage and peppers. Top with a layer of potatoes and season with salt and pepper. Pour in the half-and-half and cover the casserole with aluminum foil. Bake for 45 minutes.

Uncover the casserole and push the potatoes down with a spatula or the back of spoon to submerge them. Sprinkle with the remaining 1/4 cup cheese and bake for another 40 minutes or so.

The top of the casserole will be a rich brown, the potatoes easily pierced with a knife, and the dish will be very juicy. Let it rest for at least 20 minutes before serving.

Makes 4 to 6 servings.