Preheat the oven to 425 degrees F (218 degrees C). Line 2 baking sheets with foil or parchment paper.

In a large bowl, toss together the cauliflower, ¼ cup olive oil, salt and pepper.

Arrange the cauliflower in a single layer on the baking sheets. Roast in the oven for about 25 minutes, until browned.

Ideally the baking sheets would fit side by side, but if not, rotate them halfway through.

Meanwhile, heat the remaining tablespoon of olive oil in a cast iron skillet over medium-high heat. Add the sausage.

Cook, breaking apart with a spatula, for 8-10 minutes, until cooked and browned.

Make a well in the center and add the minced garlic. Saute for about 1 minute, until fragrant, then stir into the sausage.

Add the marinara and Italian seasoning. Simmer for 2-3 minutes, until the sauce is thick and bubbly. If needed, adjust salt and pepper to taste.

When the cauliflower is done, reduce oven temperature to 400 degrees (204 degrees C).

Arrange half of it in a single layer in the bottom of a 9x13 baking dish. Dollop half of the ricotta over the cauliflower, then sprinkle with half of the shredded parmesan. Top with half of the sausage marinara (dollop it on, then spread), and finally sprinkle with half of the shredded mozzarella. Repeat the layers with the remaining cauliflower, ricotta, parmesan, sausage marinara, and mozzarella.

Bake cauliflower ziti in the oven for 10-15 minutes, until the cheese is melted and golden.