In a large non-reactive skillet over medium heat, melt 1 tbsp unsalted butter and 1 tbsp light olive oil. Allow the butter to bubble slightly.
Season the 2 large chicken breasts all over with 1/2 tsp fine sea salt, 1/4 tsp black pepper, and 1/2 tsp garlic powder. This ensures the chicken is flavorful.
Add the seasoned chicken to the hot skillet. Sauté for 3 to 5 minutes per side or until cooked through to 165 ̊F. Look for a golden-brown color.
Remove the chicken from the pan and transfer it to a cutting board. Let it cool, then slice if desired.
In the same pan, add 1 tbsp light olive oil and 8 oz brown mushrooms. Sauté for 5-7 minutes until lightly golden.
Add the chopped 1/4 cup sun-dried tomatoes, 1/4 cup green onion, and 3 minced garlic cloves. Season with 1/2 tsp salt and 1/4 tsp black pepper. Sauté for another minute.
Stir in 1 1/2 cups heavy whipping cream and sprinkle 1/2 cup parmesan cheese over. Bring to a light boil while stirring frequently.
Reduce heat and simmer for 2 minutes until the sauce is slightly thickened. Adjust seasoning as needed.
Add 2 cups fresh baby spinach to the pan, stirring just until wilted.
Add the sliced chicken back to the pan, spooning warm sauce over it. Garnish if desired and serve immediately.
