How to Make It
Heat 1 tablespoon oil in a large nonstick skillet over medium-high. Sprinkle chicken with 1/2 teaspoon pepper and 1/4 teaspoon salt. Add chicken to pan; cook until done, about 4 minutes per side. Remove chicken from pan (do not wipe out pan).
Add remaining 1 tablespoon oil to pan. Add mushrooms and thyme sprigs; cook, stirring occasionally, until mushrooms are browned, about 6 minutes. Sprinkle flour over mixture; cook, stirring constantly, 1 minute.
Add stock and wine to pan; bring to a boil. Cook until slightly thickened, 2 to 3 minutes. Remove pan from heat. Stir in butter, remaining 1/4 teaspoon pepper, and remaining 1/4 teaspoon salt. Add chicken to pan, turning to coat. Discard thyme sprigs before serving. Sprinkle with chopped thyme, if desired.