Melt butter over med-low heat in a skillet. Add onions and celery, cook until tender (about 3 minutes). Remove from heat.
Preheat oven to 350 degrees F. In a large bowl, mix together onions, celery, stuffing mix, crab, Old Bay, garlic salt, parmesan cheese, salt & pepper.
Coat a baking dish with a thin layer of non-stick spray. Stuff a chicken breast with the crab stuffing. Secure stuffing inside of the chicken breast with two toothpicks. Place in baking dish seam side to the left. Repeat for the other three chicken breasts.
Combine the flour and paprika in a small bowl. Sprinkle mixture over the chicken breasts. Drizzle melted butter over the flour. If it seems too dry – add more melted butter.
Bake at 350 degrees F for 45 minutes. Serve alongside rice and veggies!