Saute your onions in some olive oil until they're soft and browned. Season with salt, pepper, and garlic powder.
Roast or saute your other vegetables the same way. You want them fully cooked when they go into the casserole pan.
As a last step, add all the vegetables and the salmon (broken into bite-size pieces) into a large pan and warm it all together.
Spray a 9x13 pan with non-stick spray and set aside. Preheat the oven to 350 F.
Crack the eggs into a large bowl and add the milk. Season with salt, pepper, and some garlic salt and whisk together. I use an immersion blender, which gets it nice and fluffy.
Spread your vegetables and the salmon evenly in the 9x13 pan. Gently pour the egg mixture in so it covers the vegetables and salmon.
Break up your goat cheese into pieces and sprinkle evenly over the egg mixture. Chop up the herbs and sprinkle those over as well, and lastly sprinkle the cheddar lightly over the whole thing.
Bake for 20-30 minutes, or until it's done with just a little jiggle and no raw egg patches. Let sit for 5-10 minutes once you pull it out of the oven, to set.