Preheat and Prepare: Heat the oven to 400°F. Grease a 9-inch pie plate and set it aside.

Cook the Filling: In a large skillet, cook the ground beef and onion over medium heat, breaking the meat into small crumbles. Once the beef is browned and cooked through, drain excess fat. Stir in the taco seasoning and diced tomatoes with green chiles.

Layer the Mixture: Spoon the beef mixture evenly into the prepared pie plate, spreading it to cover the bottom.

Make the Batter: In a medium bowl, whisk the milk, eggs, flour, baking powder, and canola oil together until smooth and lump-free.

Combine and Bake: Pour the batter over the beef mixture, ensuring it’s evenly distributed. Bake for 25–35 minutes, or until a knife inserted in the center comes out clean.

Add Cheese and Finish: Sprinkle the shredded quesadilla and cotija cheeses on top. Return to the oven and bake for 10 more minutes, allowing the cheese to melt and brown slightly.

Cool and Serve: Let the pie cool for about 5 minutes before slicing and serving warm.