Melt butter in skillet. Sauté onion and celery until soft and translucent. Set aside.
Combine crumbled cornbread with stuffing mix. Stir in baking powder and sage. Add cooked vegetables. Add eggs and uncooked sausage. Mix well (I use my hands). Add chicken or turkey stock to achieve a fairly mushy mixture but it should still hold together. Thin with more stock as necessary. The amount of stock is dependent upon the staleness of the cornbread. Several cups are usually needed.
Shape into 24 equal sized patties. Weigh complete batch, divide by 24, and use scale. Typically patties weigh 90-100 grams each. Got lucky today with exactly 100g!!
Place on half sheet pan (13x18) lined with reusable pan liner...4 across and 6 down. Could be frozen at this point. Freeze on pan, then bag. When ready to cook, place on pan before thawing.
Make an indentation (for a touch of gravy before serving) in the center. Bake for 30-40 minutes at 350 degrees.