Cut thighs into 1" pieces
Combine flour, salt, pepper and cayenne in a large (gallon sized) ziplock bag. Shake well to combine.
Put chicken pieces into bag and shake well to coat chicken pieces on all sides. Shake off excess. Save any flour remaining after all chicken has been coated.
Heat 2T oil in dutch oven over medium heat until shimmering. Add chicken in batches and turn to brown on all sides. Remove chicken to bowl as it gets done and continue until all chicken is browned, adding more oil as needed to prevent sticking. (Chicken will finish cooking in casserole)
Add remaining oil to empty skillet and sweat (don't brown) the vegetables until fragrant and slightly softened, about 5 minutes.
Deglaze the pan with white wine, scraping up any browned bits. Add remaining flour from dredging chicken and stir thoroughly to coat veggies. (Chicken and veggies can be prepped to this point and then frozen separately. Thaw and continue with next step)
Add chicken broth to veggies in pot and stir well. COVER pan and bake in preheated oven 25 minutes.