In a shallow bowl, combine all-purpose flour, salt, black pepper, and dried oregano. Whisk until evenly mixed.

Dredge each chicken breast fillet in the flour mixture, coating both sides thoroughly.

Heat a large skillet over medium-high heat, add olive oil and butter. Once melted, add the coated chicken fillets and sauté for 2-3 minutes per side.

In the same skillet, add more butter if needed and toss in sliced fresh mushrooms. Sauté for 4-5 minutes until browned and tender.

Return the seared chicken to the skillet and pour in marsala wine. Simmer gently for about 10-15 minutes.

Once fully cooked and the sauce thickened slightly, remove from heat and garnish with parsley. Serve hot.