Heat your oven to 350°F. Dice the chicken into bite-sized pieces and set aside. Chop your onion and mince the garlic—having everything prepped makes the next steps way faster and less stressful when you're cooking.
Heat olive oil in a large skillet over medium-high heat. Add the diced chicken and cook for 6-8 minutes until it's no longer pink inside. I always cook it just until done, not longer, because it'll cook again in the oven and you don't want it tough.
Add the chopped onion to the skillet and sauté for 2 minutes until it softens. You'll hear it sizzle slightly as it hits the hot oil—that's your cue it's cooking properly. Stir in the garlic and cook for 30 seconds until fragrant.
Sprinkle the cumin, chili powder, and paprika over the chicken mixture. Stir everything together and let it cook for 1 minute so the spices release their flavors. Remove from heat and stir in the sour cream until the filling is creamy and well combined.
Pour 1 cup of the enchilada sauce on the bottom of a 9x13 baking dish. This prevents sticking and gives you a sauce base for the enchiladas to sit on. Spread it evenly so it covers the whole bottom.
Warm the tortillas in the microwave for 30 seconds so they're pliable and won't crack when you roll them. Fill each tortilla with about 3 tablespoons of the chicken mixture down the center. When your kitchen smells like warm cilantro and toasted cumin, you're doing it right.
Roll each tortilla tightly and place seam-side down in the baking dish. Pour the remaining 1 cup of sauce over the enchiladas and sprinkle the cheddar cheese on top. Cover with foil and bake for 25-30 minutes until the cheese melts and the edges bubble slightly.