Heat a large skillet over medium-high heat and add oil to pan. Add the onion and garlic; cook for 2–3 minutes or until translucent. Add the mushrooms and cook until they are golden brown (approx. 3–4 minutes).
Flip the mushrooms, so the other side can cook. Place the spinach in the pan and cook until it is wilted or approx. 3–4 minutes. Season with salt and stir all the veggies together. Remove from heat and set aside.
In a large bowl, whisk together eggs and milk. Season with salt and pepper, to taste.
Heat another large skillet over medium heat. Spray the skillet with cooking spray and add egg mixture. Cook for 4–5 minutes, stirring frequently, until the eggs have set. Remove from heat.
Heat the tortillas in the microwave for 10 seconds (they are easier to roll when warm). Lay out the tortillas on four separate pieces of aluminum foil and spread 1-1/2 tablespoons of goat cheese on each tortilla.
Evenly distribute the roasted vegetables and scrambled eggs among the four tortillas. Roll each one up in the foil and place in a freezer bag; freeze.
When ready to eat from the freezer, remove foil and microwave on high for 1–2 minutes or until heated throughout.