Refrigerate Overnight Spread the cut side of each muffin with 1 teaspoon butter, and place, buttered side down, in a 13" x 9" x 2" baking dish.
Cook sausage in a skillet until browned, stirring to crumble. Don't drain the drippings; this is flavour. Remove from heat; add the chilies and grated cheddar cheese.
Meanwhile; beat the eggs then add the sour cream; stirring until combined.
Layer half of the sausage mixture over the split and buttered English muffins. Pour the eggs and sour cream mixture over the casserole. Finish with the remaining sausage, chilies, and cheese; cover and refrigerate 8 hours.
Remove from refrigerator, and let stand at room temperature 30 minutes. Bake, uncovered, in a preheated oven at 350°F degrees for 35 to 40 minutes.