Fill each pepper with cubed pepper-jack cheese. Pour a small amount of enchilada sauce in the bottom of each muffin cup. (You may have enchilada sauce leftover, that's ok you can use it to flavor Mexican-Rice side dish!) Place 1 (or 2 if small) cheese-filled poblano peppers into each muffin cup space.
Note: The egg mixture will expand while in the oven, and partially collapse when you bring the dish out of the oven. This is normal.