Preheat oven to 425°F (218°C). Line two baking sheets with foil or parchment paper.

In a large bowl, toss cauliflower with ¼ cup olive oil, sea salt, and pepper.

Spread florets in a single layer on the baking sheets and roast for about 25 minutes, until golden and tender.

While cauliflower roasts, heat the remaining tablespoon of olive oil in a cast iron skillet over medium-high heat. Add sausage and cook for 8–10 minutes, breaking it apart until browned.

Make a space in the center and add garlic. Sauté for 1 minute until fragrant, then stir into the sausage.

Add marinara and Italian seasoning. Let simmer for 2–3 minutes until bubbly. Adjust salt and pepper to taste.

Lower oven temperature to 400°F (204°C).

In a 9×13″ baking dish, layer half the roasted cauliflower, then dollop with half the ricotta, sprinkle half the Parmesan, spoon over half the sausage marinara, and top with half the mozzarella. Repeat with remaining ingredients.

Bake for 10–15 minutes until the cheese is fully melted and golden brown.