Heat oven to 400°F. Lightly grease mini muffin pan or line with paper baking cups.
In medium bowl, whisk together milk, melted butter and eggs. Add cornbread mix and stir until blended.
Stir in kielbasa, sauerkraut and cheddar.
Scoop batter into prepared pan, filling cups ¾ full. Sprinkle green onions over top of each muffin.
Bake 12-14 minutes or until toothpick inserted into center comes out clean.
Cool 5 minutes and remove from pan. Serve with your favorite mustard on the side.