Preheat the oven to 425F. Grease a sheet pan with a bit of oil to prevent the potatoes from sticking to the pan.
Add the potatoes, red pepper, mushrooms, red onion, and bacon pieces to the sheet pan. Toss to combine the veggies and bacon. Sprinkle the salt, pepper, and chili powder over the the veggies and bacon. Toss to combine.
Roast the veggie and bacon mixture in the oven for 15 minutes, then remove the sheet pan from the oven and, using a spoon or spatula, toss the veggies and bacon together to evenly distribute the fat (from the bacon) with the veggies. Roast the veggies for another 20-25 minutes, until soft and slightly crisp.
Remove the sheet pan from the oven and stir the spinach into the veggies and bacon. The hot veggies and bacon will wilt the spinach. I like to turn the broiler on low at this point, and place the sheet pan back in the oven for just a few minutes (3-4 minutes). This helps the veggies and bacon crisp-up a bit more. If you do this, just watch the time so the spinach doesn't burn.
While the oven is still warm (but everything is now turned off--broiler and oven), warm the tortillas by placing them directly on the oven rack. Once warm, remove the tortillas from the oven and assemble the burritos.
Scrambled Eggs:
Whisk the eggs with the milk, salt and pepper. In a large skillet, over medium-high heat, melt the butter. Add the egg mixture to the hot skillet. Once the eggs begin to set a bit on the side of the skillet (about 30-60 seconds), use a spatula to pull, lift, and fold the eggs until there isn't any liquid left. See my video tutorial and recipe for how to make scrambled eggs fluffy.
Assemble the Burritos:
Evenly distribute the veggie and bacon mixture in the center of each tortilla, followed by scrambled eggs, avocado slices, and cilantro. If you'd like, feel free to also add shredded cheese (cheddar, pepper jack, etc.) I personally don't add cheese to the burritos--they're great without it.
Serve the burritos with salsa for dipping/spooning over the top (or you can add salsa to the inside of the burritos). Serve immeadiately. This is one of many different ways to serve scrambled eggs--see all 15 Delicious Ideas for Serving Scrambled Eggs.
Notes
*I use red or Yukon Gold potatoes. Leave the skins on the potatoes, there's no need to peel! Make-Ahead Thoughts: I think these burritos would keep well in the fridge for about two days. I haven't tried freezing these burritos, but it's a shot (just try one at first). Vegetarian Option: These can easily be made without any bacon. Simply omit the bacon and toss the veggies with 1-2 tablespoons of olive oil or avocado oil. The flavor won't be quite the same (the bacon adds a nice smokey flavor), but they'll still taste great.