Place boneless chicken breasts in the slow cooker and season with cumin, chili powder, salt, and pepper.
Pour enchilada sauce over the chicken, then add sliced onions and minced garlic on top. Cover and cook on low for 4-6 hours until the chicken is tender and shreds easily.
Use tongs or forks to shred the cooked chicken directly in the slow cooker; it should fall apart easily and smell rich and spicy.
Preheat your oven to 180°C (350°F) or keep the slow cooker on warm if it has that setting. Warm the corn tortillas briefly in a skillet or microwave to prevent cracking.
Spoon a generous amount of shredded chicken and sauce into each tortilla, then roll them up tightly.
Place the rolled enchiladas seam-side down in a greased baking dish or the slow cooker insert, packing them closely together.
Pour remaining sauce over the assembled enchiladas and sprinkle evenly with shredded cheese.
Bake in the oven uncovered for about 15 minutes until the cheese is melted, bubbly, and slightly golden. If using the slow cooker, turn to warm and let sit for 15-20 minutes until cheese melts.
Remove from oven or turn off the slow cooker. Let the enchiladas rest for 5 minutes to set the filling.
Garnish with chopped cilantro or a squeeze of lime, then serve hot and enjoy the rich, smoky flavors and tender textures.
