In a large non-stick skillet, melt 2 Tbsp butter over medium heat. Add half of the chicken and cook, 4-6 minutes per side or until done.
Remove to clean plate and repeat with 2 more Tbsp butter and remaining chicken.
Using same skillet, melt remaining 1 Tbsp butter. Add minced garlic, Italian seasoning, crushed red pepper flakes, and mushrooms. Cook, stirring frequently, for 1 minute.
Deglaze skillet with white wine and chicken broth; bring to simmer; cook for 4 minutes, stirring occasionally.
Stir in heavy cream and sun-dried tomatoes; bring to simmer, cook for 5 minutes.
Add chicken back to skillet and top with fresh basil leaves. Stir gently to combine and cook for 5 minutes, until chicken is heated through, and sauce is thickened.