Set oven to 375°F.
Cook spaghetti 1 minute less than al dente. Drain.
Melt butter and brown sausage in Dutch oven.
Add onion, tomatoes, garlic, and spices. Cook 4 minutes.
Add flour, stir constantly for 1 minute.
Whisk in milk, simmer until thickened (5 mins).
Stir in spinach until wilted.
Toss sauce with cooked spaghetti.
Spread in greased baking dish.
Sprinkle cheese, bake 18–20 minutes until bubbly.
Cool 5 minutes, garnish with parsley, slice and serve.
