Heat a large non-stick skillet over medium-high heat. Add sausage to pan; sauté 4 minutes, stirring to crumble. Add onion, celery, and butter to pan; sauté 5 minutes, stirring occasionally. Stir in sage, thyme, salt, and pepper; cook 1 minute. Stir in celery leaves.
Combine chicken stock, oil, and beaten eggs in a medium bowl, stirring with a whisk.
In another medium bowl, combine baking powder and corn bread mix. Add stock mixture and onion mixture, stirring just until moist. Spray your muffin tin for 12 with cooking spray. Spoon batter into each cup, then sprinkle with chopped pecans.
Bake at 400° for 12 minutes or until lightly browned.