If your chicken breasts are thicker than ½” slice them in half horizontally to create two filets, or pound to ¼” thickness in a gallon zip top bag.
Pat dry with paper towel. Season chicken generously with salt, pepper, and paprika just before cooking.
Heat a large heavy-bottomed skillet over medium high heat. Add enough olive oil to coat the bottom of the pan. Working in batches so the pan is not crowded, saute chicken breast undisturbed 3-5 minutes per side, until chicken is golden brown and just cooked through to 165℉. Remove to a plate to rest.
Reduce heat to medium-low, add 1 tablespoon of butter, followed by the garlic, and saute for 30 seconds.
Add flour if using, whisk for 1-2 minutes until flour is fully cooked. Add wine and scrape up brown bits on the bottom of the pan with a wooden spoon.
Add the dijon mustard, garlic powder, and chicken stock, whisking constantly. Increase heat to medium and add the remaining butter, whisking to incorporate.
Return the chicken to the pan, followed by the parsley. Simmer for about 1 minute, coating the chicken in the sauce.
Turn off the heat, taste sauce and adjust seasoning if needed. Serve immediately.