Pat dry your shrimp with paper towels. Season with the Italian seasonings.
In a large skillet over medium-high heat, melt the butter and olive oil. Once pan is hot, add in the seasoned shrimp and cook for 1-2 minutes on each side. Transfer to a plate and set aside.
To the same pan, add in the onion and sauté on medium heat for 3-4 minutes. If you need some oil in the pan, add in a drizzle. Next stir in the garlic for 30 seconds. Sprinkle in the flour and stir to incorporate.
Stir in the chicken stock and sun-dried tomatoes and allow to cook for a few minutes. Add in the half & half, salt, pepper, and parmesan and stir. Bring to a simmer and stir for a few minutes to thicken the sauce. Add in the baby spinach and shrimp. Stir for a few minutes to heat the shrimp and wilt the spinach.