Line a 13x9 pan with parchment paper and set aside.
Preheat the oven to 375° and line a baking sheet with parchment paper. Place the potatoes on it and drizzle with the avocado oil and sprinkle with the salt. Toss to mix and bake until fork tender, 25-35 minutes.
While the potatoes cook, prepare the rest of the casserole. Add the tablespoon of oil to a large skillet, add the peppers and cook over medium heat until tender, about 5 minutes. Add in the breakfast sausage and salt and cook until browned, about 5-10 minutes. Take off the heat and dump into the prepared pan. Spread as evenly as possible.
Remove the potatoes from the oven and add them to the pan, spreading evenly. Add the green onions on top.
Crack the eggs into a large bowl and add the almond milk. Whisk until all the yolks are broken and mixture is smooth. Pour on top of the peppers and potatoes and mix everything around to make sure it's even.
Bake for 35-40 minutes, until it is set all the way through. Test by jiggling it and making sure no spots are wet.