Preheat oven to 350 degrees. Brush a 10-by-15-inch rimmed baking sheet or jelly-roll pan with oil. Line bottom of pan with parchment, leaving a 1-inch overhang on the two shorter sides. Brush parchment with oil.
In a bowl, whisk together milk and flour. Add eggs, mustard, 1 teaspoon salt, and teaspoon pepper; whisk to combine. Pour into pan. Sprinkle spinach over top in an even layer.
Bake until edges of omelet are set, 10 to 12 minutes. Sprinkle with cheddar; bake until cheese has melted, 2 to 4 minutes. Beginning at one shorter end, lift parchment, and roll up omelet tightly, peeling back parchment as you go. Slice and serve.
I made this for my husband and I for Sunday brunch - what a waste of money. First, it didn't set well enough to roll properly. I don't know what went wrong there but I think it's too much spinach and cheese and not enough egg. Definitely needs more time in the oven. Second, you could taste the flour. I don't know what purpose the flour was supposed to serve. Looked awful, tasted just as bad.
The day I made this my oven stopped working--I ran to my neighbor and she baked it for me and the end result was still wonderful. There are only 2 of us and I just cut off when I needed for the next few days. This makes such a beautiful presentation, I am sure even spinach haters would love it.
Sounds wonderful for having guests over, I would also serve a tomato and fresh basil salad with it. You can also make the omlet with diced fresh tomatoes, feta cheese and fresh basil. Yummy!
Made it and loved it: http://marthaandme.wordpress.com/2009/04/10/omelet-fun/
If you don't like spinach you could use anything you would normally use in an omelet - mushrooms, cheese and ham, etc.
What could I substitute for the spinach? My kids don't like it.
This is great! Really Great! The only thing I will do differently next time is add one package of spinach instead of two. The possibilities here are endless, you could add anything to this I would imagine. Next time I think I'll try some tomatoes, ham and leftover hash browns.