To make the kids' sandwich: Crack two eggs into a small bowl. Add the milk and Parmesan, and lightly beat until combined.
Heat a teaspoon of oil in a small saute pan over medium-low heat, and add the egg mix. Slowly scramble the eggs until just set and fluffy.
Place the scrambled eggs on 1 toasted English muffin half, and top with 1/2 cup Cheddar. You can let the cheese melt naturally or place it under the broiler to get it browned and bubbly (which is the right decision in life). It's done!
Now to make your sandwich: Heat another teaspoon of oil in your saute pan. Add the spinach and wilt, about 20 seconds. Remove from the pan and add the red onion and sun-dried tomatoes. Let them sear and blister for about a minute. Remove and place them with the spinach.
If you need to add a little more oil at this time, go for it. Crack the remaining egg into the saute pan and let fry until the white is set but the yolk is still runny, about 2 minutes. Sprinkle with salt and pepper.
In the meantime, place the remaining 1/4 cup cheese on the top half of the English muffin, and toast in the broiler until the cheese melts.
Place the spinach, red onion and sun-dried tomatoes on the bottom half of the toasted muffin. Then layer with the fried egg and cheesy top half.