Preheat oven to 350°F.
Melt 4 tablespoons of butter in a large pan over medium heat and sauté onion, celery
and carrots for 10 minutes. Add garlic and sauté for 2 more minutes.
While veggies cook, butter or spray sides of 11 x 13 baking dish then pour cornbread croutons into the dish.
When vegetables are cooked, add to cornbread.
In a large bowl add remaining butter (melted) chicken stock, eggs, sage and poultry seasoning.
Pour stock mixture over bread crumbs completely covering the bread.
Gently fold in blueberries.
Bake for 1 hour covered in aluminum foil. Uncover and bake for 15 more minutes or until golden brown.