Season chicken on both sides with salt, 1/2 tsp pepper, and paprika. Add flour to a shallow dish, then dip chicken into flour to fully coat
Heat olive oil in a heavy skillet over medium high heat until hot. Add butter, then add flour-dredged chicken to skillet being careful not to overcrowd the pan (you may need to brown the chicken in batches if your pan is less than 12 inches in diameter)
Cook chicken for 4 - 5 minutes per side until cooked through and golden brown. Remove to a plate and set aside
Reduce heat to medium low and add a small drizzle of oil to pan. Add shallots and cook for 2 - 3 minutes until soft and fragrant. Add garlic and cook for another 30 seconds or so
Carefully add the chicken broth, deglazing the pan. Pour in heavy cream and stir well to combine (add spinach here if desired)
Cook for a while, (15+ minutes), until thickened. Add parmesan, remaining 1/4 tsp of pepper and Italian seasoning (or whatever spices you want). Add chicken back to skillet, nestling and moving around to help thicken the sauce even more. Continue cooking until sauce is very thick