1. Heat oven to 425 degrees.
2. Cover a rimmed baking sheet with foil and arrange tomatoes and sliced sausage in a single layer. Drizzle the tomatoes with about 1/2 tablespoon of olive oil and season with Italian seasoning, salt, and pepper. Toss to coat.  Roast the tomatoes and sausage in the oven until the tomatoes are tender and the sausage is golden brown. Remove from oven and set aside.
3. While the sausage and tomatoes are roasting,  add 1 1/2  tablespoons of olive oil to a large skillet over medium-high heat.  Toss in the diced onions. Once onions begin to caramelize, about 5 minutes, add the garlic. Cook garlic and onions for an additional minute, or until garlic is fragrant. Add water, and milk. Cover and bring to a boil.
4. When water is at a full boil, add spaghetti and red pepper flakes. Reduce the heat to medium, and cover. Allow spaghetti to cook until al dente (see package directions for cook time), stirring occasionally.
5. Remove lid from skillet. Stir in tomatoes, spinach, chicken sausage, salt and pepper. Stir constantly until liquid is mostly absorbed. Remove skillet from the heat.
6. Add a squeeze of lemon juice, 1/2 teaspoon of lemon zest and parmesan cheese into the skillet. Stir until fully combined, about 1 minute. Taste and season with salt and pepper as needed. Serve immediately. 

TOPPINGS: add a few healthy dashes of hot sauce as a fun topping. I like to do this on individual plates so everyone can control their own spice level.