Place chicken breasts between two sheets of plastic wrap. Pound to 2cm (3/4-inch) even thickness. Pat completely dry, then season both sides with salt, pepper, and garlic powder.
Heat olive oil in a large skillet over medium-high until shimmering. Add chicken in a single layer. Sear undisturbed for 5 to 6 minutes until a deep golden crust forms. Flip, cook 4 to 5 minutes more until internal temperature reaches 75°C (165°F). Remove and rest on a plate.
Reduce heat to medium. Add garlic and red pepper flakes to the same pan. Stir for 1 minute until fragrant and just golden. Add sun-dried tomatoes and Italian seasoning, cook 1 to 2 minutes more.
Pour in chicken broth. Scrape the pan bottom to lift all browned bits. Simmer 2 minutes. Reduce to medium-low, add heavy cream and thyme. Simmer gently for 3 to 4 minutes, stirring occasionally, until the sauce coats the back of a spoon.
Remove pan from heat. Stir in parmesan in two additions until fully melted and sauce is smooth.
Return chicken to the pan. Spoon sauce over each breast. Simmer on low for 5 to 7 minutes until chicken reads 75°C (165°F). Scatter torn basil over the top and serve immediately.