Set up the slow cooker. Lightly spray the insert. Add 1 1/2 cups of the enchilada sauce, the salsa, onion, garlic, cumin, chili powder, smoked paprika, salt, and pepper. Stir to combine.

Add the chicken. Nestle chicken breasts into the sauce. Spoon some sauce over the top so every piece is coated.

Cook low and slow. Cover and cook on Low for 4–6 hours or on High for 2 1/2–3 1/2 hours, until the chicken shreds easily with two forks. Avoid lifting the lid often; it extends cook time.

Shred the chicken. Transfer the chicken to a cutting board and shred with two forks. Return it to the slow cooker and stir to coat in the sauce. Taste and adjust seasoning if needed.

Preheat the oven. Set your oven to 375°F (190°C). Grease a 9x13-inch baking dish. Spread a thin layer of the remaining 1/2 cup enchilada sauce across the bottom.

Warm the tortillas. For flour tortillas, wrap in a damp towel and microwave for 20–30 seconds. For corn tortillas, lightly warm in a dry skillet or briefly steam so they don’t crack.

Assemble the enchiladas. Spoon a generous line of the chicken mixture down the center of each tortilla. Add a sprinkle of cheese. Roll snugly and place seam-side down in the baking dish. Repeat until the dish is full.

Sauce and cheese. Pour any remaining sauce from the slow cooker over the top, then drizzle the rest of the enchilada sauce if needed to lightly cover. Finish with the remaining shredded cheese.

Bake. Bake uncovered for 12–15 minutes, until the cheese is melted and bubbling and the edges are lightly crisp.

Finish and serve. Let the enchiladas rest for 5 minutes. Top with cilantro, avocado slices, a dollop of sour cream, and a squeeze of lime. Serve hot.