Preheat oven to 400°F (200°C). Spray an 17 by 12-inch rimmed baking sheet with non-stick cooking spray.
For the seasoning: In a small mixing bowl whisk together chili powders, cumin, paprika, coriander, 1 1/2 tsp salt and 1/2 tsp pepper, set aside.
For the fajitas filling: Spread bell peppers and yellow onion onto baking sheet.
Roast in preheated oven, tossing once halfway through cooking, until veggies are tender and chicken has cooked through, about 18 - 25 minutes (test a few of the larger pieces to make sure they are 165 in the center).
Wrap tortillas tightly in foil and warm in oven during last 5 minutes of fajita filling cooking.
Recipe source: Cooking Classy, inspired by my Slow Cooker Fajitas
You don't need to line your sheet pan with foil or parchment paper, non-stick spray does the job!
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