Prepare the filling: In a large bowl, combine the cooked chicken, tomatillo salsa, diced onion, diced jalapeño, minced garlic, chopped cilantro, and Monterey Jack cheese. Season with salt, black pepper, garlic powder, cayenne pepper, and chili powder to taste. Mix well until everything is evenly combined.

Assemble the chimichangas: Lay the flour tortillas flat on a clean surface. Evenly divide the chicken mixture among the tortillas, placing it in the center of each tortilla. Roll up the tortillas tightly, folding in the sides as you go, to form a burrito-like shape.

Fry the chimichangas: Heat about 1 inch of vegetable oil in a large skillet over medium-high heat. Once the oil is hot (you can test it by dropping a small amount of tortilla scrap in the oil; if it sizzles, it’s ready), carefully add the chimichangas seam-side down into the oil.

Cook and crisp: Fry the chimichangas for about 2-3 minutes per side, or until golden brown and crispy. Use tongs to flip them gently, ensuring both sides are evenly fried.

Drain and serve: Once crispy and golden, remove the chimichangas from the oil and drain on paper towels. Serve immediately with your favorite toppings, such as sour cream, guacamole, or salsa.