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

Toss cauliflower with 1 tbsp oil (dbl for 4 ppl) on a baking sheet. Season with 1/4 tsp garlic salt (dbl for 4ppl) and pepper. Roast in the middle of the oven, until golden-brown, 14-16 min.

While cauliflower cooks, add rigatoni to the pot of boiling water. Cook, uncovered, stirring occasionally, until tender, 10-12 min. Reserve 1/2 cup pasta water (dbl for 4 ppl). Drain, then return to the same pot. Set aside, off heat.

Heat a large non-stick pan over medium heat. When hot, add 1 tbsp butter (dbl for 4ppl) then onions. Cook, stirring often, until softened, 3-4 min. Sprinkle over flour and 1/2 tsp garlic salt (dbl for 4ppl). Cook, stirring often, until coated, 1 min. Add 1/2 cup milk (dbl for 4 ppl) and bring to a boil. Cook, stirring often, until thickened, 1 min. Remove the pan from the heat and add spinach. Stir, until wilted, 1 min.

Stir sour cream and cheddar cheese into sauce. Season with salt and pepper. Add cheese sauce, reserved pasta water and half the cauliflower to the pot with rigatoni. Stir until cheese melts, 1 min.

Divide pasta between bowls and top with remaining cauliflower. Sprinkle over chives and 1/4 tsp chili flakes (NOTE: Reference Heat Guide).