Season 4 chicken breasts on both sides with 1 teaspoon salt, ½ teaspoon black pepper, 1 teaspoon paprika, and 1 teaspoon garlic powder.
Heat 2 tablespoons olive oil in a large skillet over medium-high heat. Add the chicken and cook for 5 to 6 minutes per side, until golden brown. The chicken does not need to be fully cooked at this stage. Remove from the skillet and set aside.
Reduce the heat to medium and add 3 tablespoons butter to the same skillet. Once melted, add 1 sliced onion and cook for 8 to 10 minutes, stirring often, until soft and lightly caramelized.
Stir in 2 minced garlic cloves and cook for 30 seconds, just until fragrant.
Sprinkle 3 tablespoons flour over the onions. Stir constantly for 1 minute to cook out the raw flour taste.
Slowly pour in 2 cups chicken broth, stirring as you go. Let the gravy simmer for 3 to 4 minutes, until thickened.
Stir in ½ cup heavy cream, 1 teaspoon Worcestershire sauce, ½ teaspoon dried thyme, and ½ teaspoon black pepper. Taste and adjust salt as needed.
Return the chicken to the skillet, nestling it into the gravy. Spoon the sauce over the top, reduce the heat to low, cover, and simmer for 15 minutes, until the chicken is fully cooked and tender.
Garnish with chopped parsley and serve hot.