Rinse chicken breast under cold running water, pat dry, and cut into strips. Clean mushrooms. Halve bell pepper, remove stem and core, rinse, pat dry, and dice finely.
Heat butter in a large pan over medium-high heat. Add chicken strips and mushrooms, cook for 5 minutes, stirring occasionally. In a small bowl, whisk together chicken broth and flour until smooth. Pour broth mixture and diced pepper into pan, stir well. Add cream and stir. Reduce heat to medium and simmer for 5 minutes, stirring frequently, until sauce thickens. Verify chicken has reached 74°C/165°F internal temperature. Season with salt, pepper, and lemon juice to taste.
Rinse parsley, pat dry, and pluck leaves from stems. Arrange fricassee on plates and garnish with parsley leaves. Serve with butter rice.