Cut squash in half and the remove seeds. Spray a baking sheet with olive oil cooking spray. Spray the cut sides of the squash as well and place cut side down on the baking sheet. Bake at 375 degrees for 30 minutes. The shell should give slightly when pressed with a finger. Turn right-side up and allow to cool a bit.
Heat 2 teaspoons of the olive oil in a medium fry pan. Add the onion and cook for 1 -2 minutes. Crumble the sausage into the pan and add the garlic. Cook 5 - 7 minutes until the sausage is cooked, stirring often.
Add the tomato paste and raise the heat to medium high. Stir to coat the sausage mixture. Cook for 3 minutes adding chicken broth as needed to prevent scorching.
Add the marinara sauce to the pan and reduce the heat to low. Simmer 15 minutes, stirring occasionally. Remove from heat
In a small pan heat the remaining teaspoon of olive oil. Add the spinach and Italian herb blend. Cook stirring frequently until the spinach is wilted. This should take 2 - 3 minutes. Remove from heat and allow to cool.
Combine the ricotta, egg, garlic powder, and 2 tablespoons of the Romano cheese in a small bowl. Stir in the cooled spinach.
Use a fork to loosen the squash threads slightly.
Divide the ricotta mixture between the two squash halves.
Spoon the sausage mixture on top of the ricotta.
Sprinkle with the remaining tablespoon of Romano Cheese.
Top each half with the Italian cheese blend.
Bake uncovered at 375 degrees for 20 - 25 minutes. If you prepared and assembled ahead of time increase the cooking time to 30 minutes or so. The mixture should be bubbling slightly.
Turn oven to broil and cook until the cheese is light golden, about 2 -3 minutes. Remove from oven and allow to rest 5 minutes before serving.