Cut chicken breasts in small pieces, season with salt and pepper; sprinkle flour over chicken pieces and toss so that each piece of chicken is slightly coated with flour.
Place frozen peas in a pot with hot water and set aside.
Heat olive oil in a large skillet and add chicken. Cook chicken until no longer pink. Add onions and garlic and stir. Cook until onions are translucent and chicken starts to brown. If you need some liquid, add a bit of chicken broth to the skillet.
Add mushrooms to skillet and cook on medium heat for about 5 minutes. Add peas, chicken broth, white wine and season with salt and pepper as preferred. Cook uncovered until sauce is almost all reduced.