Preheat oven to 350 degrees. Coat a large casserole dish with pan spray. Break up cornbread into small pieces and put into a large mixing bowl. Place a large skillet over medium-high heat, add cut-up sausage, and cook for 8-10 minutes. Remove sausage and set aside. To the same pan, add butter; when melted add onions, celery and garlic. When vegetables become tender, add the sage and stir in to blend. Pour all the cooked vegetables and sausage over the cornbread. Add the whisked eggs, beer and stock. Season with salt and pepper. Form into casserole dish. Cover with foil and bake at 350 degrees for 30 minutes.