Combine chicken broth and cornstarch, stirring well; set aside.
Place chicken between 2 pieces of heavy-duty plastic wrap; pound to 1/2-inch thickness, using a meat mallet or rolling pin. Coat with cooking spray; sprinkle with salt and pepper.
Sprinkle 2 tablespoons breadcrumbs evenly over each chicken breast half; coat with cooking spray.
Place a large nonstick skillet over medium heat until hot; add chicken. Cook 3 minutes on each side or until done.
Remove chicken from pan; cover and keep warm.
Heat same skillet, coated with cooking spray, over medium-high heat.
Add mushrooms and shallots; cook 4 to 5 minutes or until tender, stirring occasionally.
Add wine; cook 1 minute.
Add chicken broth mixture; cook 2 to 3 minutes or until sauce is thickened.
Remove from heat; add butter, stirring until butter melts.