Place chicken breast in slow cooker. Pour frozen veggies over the chicken (no need to thaw). Pour 3-4 cups white sauce (or cream of soups) over the chicken and veggies. Add water to completely cover chicken. Cook on low for 8 hours.
Prepare and bake your cornbread. Here's my GF Skillet Cornbread Recipe that is amazing!
About 1 hour before the slow cooker is done cooking, add the cornbread, crumbled into pieces (or top with the biscuits).
Steam broccoli in steamer for 3-5 minutes or microwave for 3 minutes. Serve on the side with chicken and dumplings.