- Preheat oven to 400 degrees F. Spray 9″ x 13″ baking dish with cooking spray and set aside.
- Cook pasta as per package instructions. Drain and transfer to a large mixing bowl along with riced/chopped cauliflower. Set aside.
- Preheat large skillet on low heat and add olive oil, onion and garlic. Cook for 2 minutes, stirring occasionally. Add flour and cook for another minute or until flour is well combined. Whisk in milk, raising heat to medium – high, and bring to a boil. Reduce heat to low – medium and cook for 5 minutes.
- Remove from heat, add 1 cup of cheese, salt and pepper; stir until sauce is smooth. Pour into the bowl with pasta and cauliflower, mix well. The mixture should be thick and not saucy.
- Transfer mixture to previously prepared baking dish, level with spatula and top with remaining cheese. Bake uncovered for 25 minutes or until cheese is bubbly and golden crust and edges appear.
- Remove from the oven, cut into 9 slices and serve hot.
Store: Refrigerate in an airtight container for up to 3 days or freeze leftovers for up to 3 months.
Freeze: Assemble, tightly wrap with plastic and then foil, and freeze for up to 3 months. Thaw in the fridge overnight and bake as per instructions + 15 minutes.
Make Ahead: Assemble, cover and refrigerate for up to 48 hours. Bake as per instructions.