Preheat oven to 400°F Mix Jiffy, milk, and egg in a small bowl. Mix until all ingredients are well blended but not over beaten/mixed. Place into an 8x8 baking dish (or cake pan) and bake for 15-20 minutes. (This step is all from package directions).
Remove from oven and immediately spread the butter over top of cornbread until butter is melted and bread is fully coated on top.
Immediately cover with aluminum foil, creating a tight seal around the pan. Wait 10-15 minutes before slicing and serving.
The foil steams in the butter and makes a normally gritty cornbread nice and smooth and creamy. The leftovers (if any), also keep better as it retains it's moisture. Simply microwave any leftover slices for about 20 seconds and serve!