Prepare a grill fire to about 350° with hickory for smoke flavor.
Crumble biscuits and toast. Add to a large bowl and add in crumbled cornbread and chicken. Set aside.
In a large skillet, melt butter and add diced onions, celery and bell peppers. Cook over medium heat. Stir often until vegetables are softened, about 10 minutes.
Stir in Cream and pour over cornbread mixture.
In another bowl, beat 2 eggs with 2 cups of chicken broth and pour over bread and chicken.
Next, add sage, garlic, salt and pepper, stir until well combined.
Add additional broth, 1/2 cup at a time, until mixture is very moist but not soupy.
Make an 8 x 10 foil pan with 2 layers of heavy foil (or use a store bought foil pan). Spray with non stick cooking spray and place on a grill pan.
Pour dressing mixture into pan and spread evenly. Cover with foil.
Cook over indirect fire for about 1 hour with the grill closed.
Next, remove foil cover and cook an additional 30 minutes or until dressing is cooked through.
Remove from grill.
Slide dressing onto a serving platter and serve immediately.