Prep the Chicken:
Slice the chicken breasts into 1-inch bite-sized pieces. Season generously with salt, pepper, and garlic powder. Lightly dredge each piece in flour.

Brown the Chicken:
Heat 2 tablespoons of olive oil in a deep skillet over medium-high heat. Sear the chicken in two batches, cooking for about 3 minutes per side until golden and cooked through. Add the remaining oil between batches as needed. Remove chicken and set aside.

Sauté the Vegetables:
In the same skillet, melt the butter. Add the sliced mushrooms and chopped onions. Sauté for 6–8 minutes until the mushrooms are browned and their moisture has evaporated.

Add Flavor Boosters:
Stir in the minced garlic, Dijon mustard, and Worcestershire sauce. Cook for 1 minute, stirring to release all the aromas.

Deglaze the Pan:
Pour in the chicken broth, scraping up the browned bits from the bottom of the pan. Return the cooked chicken to the skillet.

Simmer Together:
Simmer for about 2 minutes over medium heat, allowing the flavors to meld.

Add Sour Cream:
Reduce the heat to low. Stir in the sour cream until well combined. Warm gently for 1–2 minutes—do not boil to prevent curdling.

Taste and Serve:
Adjust seasoning with extra salt or pepper if needed. Serve immediately over pasta, rice, or mashed potatoes. Garnish with parsley if desired.