In an eight inch nonstick pan, melt one Tbsp. of butter on medium heat and add onions, occasionally stirring. Allow to cook until they have softened and begin to brown. Add the peppers, stir, and salt to taste. Cook until they begin to soften. Add the spinach and allow it to wilt for a couple of minutes. Transfer this filling to a bowl.
Put your pan back on the heat and add one Tbsp. of butter, melting on medium heat. Add your hash browns and season with salt and pepper to taste, stirring until the butter and seasoning are evenly distributed. Arrange the potatoes in a flat even layer. Sprinkle cheese evenly on top and allow it to melt. Then, sprinkle the filling evenly on top.
When the bottom of the hash browns has crisped up and browned, your hash brown omelette is ready. Shake the pan to make sure it's not sticking to the bottom, then bring it over to your plate and carefully tilt the pan, using the edge to help fold it over in half. Add your favorite toppings and enjoy!