Pat the chicken dry with paper towels. If using whole breasts, slice them horizontally to create thinner cutlets or cut into 1-inch pieces for quicker cooking. Season chicken with salt and pepper.

Heat 1 tablespoon of olive oil in a large skillet over medium-high heat. Add the chicken and sear for 3-4 minutes per side (if cutlets) or until golden brown and cooked through if diced. Remove chicken from the skillet and set aside on a plate.

Reduce heat to medium. Add the remaining 1 tablespoon of olive oil to the same skillet. Add minced garlic and sauté for 30 seconds until fragrant, being careful not to burn it.

Pour in the chicken broth and scrape up any browned bits from the bottom of the pan with a wooden spoon. Bring to a simmer and let it reduce slightly for 1-2 minutes.

Stir in the heavy cream, basil pesto, chopped sun-dried tomatoes, and red pepper flakes (if using). Whisk until well combined and the sauce begins to gently simmer.

Stir in the Parmesan cheese until melted and the sauce is smooth and slightly thickened. Taste and adjust seasoning with salt and pepper if needed.

Return the cooked chicken to the skillet with the creamy pesto sauce. Toss gently to coat the chicken evenly. Let it simmer for another 1-2 minutes to allow the flavors to meld and chicken to warm through.

Garnish with fresh chopped basil and additional Parmesan cheese, if desired. Serve immediately over cooked pasta, rice, mashed potatoes, or with a side of crusty bread.