Cook the pasta according to instruction on package, rinse in cold water and set aside. Preheat the oven to 400 F (205 C).
Add 2 tsp oil in a baking dish. Sprinkle the onion, garlic, a third of the sage and pepper flakes and a pinch of salt. Bake for 6 to 8 mins.
Meanwhile, blend the sauce ingredients until smooth. Taste and adjust salt and flavor.
Add the cooked pasta to the baking dish. Add the sauce and toss well. Add some sage and mix in.
Mix the breadcrumbs with the remaining sage, salt and olive oil in a small bowl.
Spread the breadcrumb topping on the pasta. Bake for 20 to 25 mins. Broil for a minute. Let it sit for a few mins before serving.
To freeze: Bake the mac with half the breadcrumb topping for 20 mins, cool completely and freeze the container. Use foil to seal the top surface of the mac and cheese to avoid freezer burn, or transfer portions to containers whih fit the mac with the least air space on top.To reheat: Thaw overnight, add breadcrumb topping and bake for 15 mins or so until heated through and golden on top.
Gluten-free: Use gluten-free pasta and breadcrumbs or use 3 tbsp almond meal instead of breadcrumbs to make the topping. You can use any squash puree in this bake.If using dried sage, use a mix of rubbed and ground, about 2 tsp rubbed and 1/2 to 1 tsp ground. Dried ground sage is generally a strong flavor as it gets compacted, so use less to begin with and add more as needed. Nutrition is for 1 Serve