In a large (10- inch) skillet over medium heat melt the butter and olive oil together.
Add in the chopped onions and cook for 5 minutes on medium-high heat to caramelize.
Add in the garlic the last 2 minutes of cooking the onions.
Add in the Red Sauce, chicken broth, crushed red pepper, and salt and pepper, stir to combine.
Add in the linguine and stir carefully into the sauce.
Turn the heat up to medium-high and bring the sauce it a boil.
Once it’s boiling reduce the heat to medium-low and simmer for 15-20 minutes, stirring occasionally so the pasta doesn’t stick together.
When there are about 5 minutes left to cook the pasta add in the shrimp and spinach and stir to combine.
Cook for about 2 more minutes until the spinach has wilted.
Sprinkle with parmesan cheese and parsley.