1batch Homemade German Spätzle (about 5 cups cooked Spätzle, can use store-bought if preferred), can be made in advance and refrigerated until ready use, then let warm to room temperature before baking.
2very large onionschopped
12ouncesshredded Emmentaler or Jarlsberg (Swiss-like from Norway, mild)(you can also add some Gruyere for extra flavor)
Preheat the oven to 400 degrees F.
Butter a 9x13 (or a little smaller) casserole dish.
Layer 1/3 of the Spätzle in the bottom of the dish followed by 1/3 of the cheese and 1/3 of the caramelized onions. Repeat, sprinkling each layer with some salt, ending with cheese and onions on top.
Bake for 10 minutes or longer until the cheese is melted and the edges are just beginning to get a little crispy.