Before starting, preheat the oven to 425°F. Wash and dry all produce.Heat Guide for Step 6: 1/4 tsp (1/2 tsp) mild, 1/2 tsp (1 tsp) medium and 1 tsp (2 tsp) spicy! Add 10 cups water and 2 tsp salt to a large pot (use same for 4 ppl). Cover and bring to a boil over high heat. Meanwhile, cut cauliflower into bite-sized pieces. Peel, then cut half the onion (whole onion for 4 ppl) into 1/4-inch pieces.

Add cauliflower and 1 tbsp (2 tbsp) oil to an unlined baking sheet. Season with half the garlic salt and pepper, then toss to coat.Roast in the middle of the oven, until golden-brown, 14-16 min.

Meanwhile, add rigatoni to the boiling water. Cook uncovered, stirring occasionally, until tender, 10-12 min. Reserve 1/2 cup (1 cup) pasta water, then drain and return rigatoni to the same pot, off heat.

Heat a large non-stick pan over medium heat. When hot, add 1 tbsp (2 tbsp) butter, then onions. Cook, stirring often, until softened, 3-4 min. Sprinkle flour and remaining garlic salt over onions. Cook, stirring often, until onions are coated, 1 min. Add cream and 1/2 cup (1 cup) milk, then bring to a boil. Once boiling, cook, stirring often, until sauce thickens, 1 min. Remove from heat, then add spinach. Stir until wilted, 1 min.

Add cheese, sauce, half the reserved pasta water and cauliflower to the pot with rigatoni. Stir until cheese melts, 1 min. (TIP: For a lighter sauce consistency, add more reserved pasta water, 1-2 tbsp at a time.) Season with salt and pepper, to taste.

Divide cheesy creamy cauliflower pasta between bowls. Sprinkle 1/4 tsp (1/2 tsp) chili flakes over top. (NOTE: Reference heat guide.)