Add the boneless skinless chicken breasts, all-purpose flour, salt, and black pepper to a large zip-top bag. Seal the bag and shake to fully coat the chicken with the flour and seasonings. Remove the coated chicken breast from the bag, being sure to shake off any excess flour, and set the chicken on a plate. Discard the bag and excess flour.

In a large 12-inch skillet, on medium-high heat, add the olive oil. Once the oil and skillet are hot, add the chicken breasts (be sure to shake off any excess flour from the chicken before placing them into the hot skillet) and cook for 5-7 minutes on each side or until golden brown. You may need to cook your chicken in two batches to avoid overcrowding your skillet. Once all the chicken has been browned, remove the chicken from the skillet and place it on a plate and set aside.

Wipe out any remaining oil and overly browned flour from the skillet using a dry paper towel. This is especially important if you had to cook your chicken in 2 batches.

Turn the heat to medium and add the butter, chopped sweet yellow onion, diced sundried tomatoes, minced garlic, Italian seasoning, and red pepper flakes. Stir to combine and cook for 2-3 minutes or until the onions are tender.

To the skillet, stir in the chicken stock and heavy cream. Allow the liquids to come to a low boil, then reduce the heat to medium-low and add the grated parmesan cheese and chopped basil. Stir to combine. Add the chicken back to the skillet. Make sure not to coat the chicken in the sauce, as you want to keep the flour coating on the top of the chicken as crisp as possible. Allow the chicken to gently finish cooking in the simmering sauce for 15-20 minutes.

Once the chicken has finished cooking, you can remove the skillet from the heat and spoon some of the sauce over the top of the chicken before plating and serving.