Preheat the oven to 350°F. Line a baking sheet with foil and set aside.
In a medium skillet, cook the ground beef over medium-high heat, crumbling it as it cooks. If there is excess oil after cooking the beef, drain it and return the skillet to the heat.
Stir in the taco seasoning until the beef is well coated. Add the diced onions and cook until they begin to soften.
Once the beef is almost cooked through and the onions are translucent, stir in the chopped green chiles and enchilada sauce. Remove from heat and set aside.
Cut the tops off each bell pepper and remove the seeds and ribs from the inside.
Place the hollowed-out peppers on the prepared baking sheet.
Stuff each pepper with a generous amount of the beef mixture, followed by a layer of shredded cheese, and then more beef mixture. Top with additional shredded cheese.
Place the pepper tops back on each stuffed pepper.
Bake in the preheated oven for 30-40 minutes, or until the peppers are tender and the cheese is melted and bubbly.
Serve the stuffed peppers immediately, garnished with sour cream and cilantro if desired.
Enjoy these Cheesy Mexican Stuffed Peppers for a flavorful and satisfying meal!