Add the salt, garlic powder, onion powder, paprika and black pepper to a small bowl and stir to combine.
Cut each chicken breast in half, lengthwise to make two thinner pieces. Pound each piece down to about ¼ inch thick using a meat mallet. Season the chicken on both sides with the prepared seasoning mix.
Clean the mushrooms and slice them. Don't slice them too thin so they hold up in the sauce.
Heat the olive oil in a large, deep skillet over medium heat. When the oil is hot, add the chicken.
Cook 3-5 minutes on each side (depending on the thickness) until the chicken is golden brown and cooked through.
Make sure the internal temperature of the chicken at its thickest part is at least 165°F
Remove the skillet from the heat. Remove the chicken from the skillet and place it on a plate or pan and keep warm.
Do not wash the skillet. Place it back over medium heat and add the butter.
When the butter is melted and foaming add the mushrooms. Cook the mushrooms for 1-2 minutes, stirring frequently.
Sprinkle the flour over the mushrooms, stirring well to mix. Cook the mushrooms for 2 minutes, stirring frequently.
Slowly add the chicken broth to the mushroom mixture, while stirring and gently scraping any bits off the bottom of the skillet. Use a wooden spoon or spatula, moving in small circles around the pan.
Bring the mushroom sauce to a simmer and cook for approximately 5 minutes (or until it thickens), stirring occasionally. Taste the mushroom sauce and add salt and pepper, to taste, if needed.
Add the chicken back to the skillet. Turn it to coat with the mushroom sauce. Then, lower the heat to medium-low, cover and cook about 5 minutes to warm through.