In a large skillet, melt the butter over medium heat. Add the diced white onion and sauté until translucent. Stir in the flour and cook for another minute. Gradually whisk in the milk until the mixture is smooth and thickens slightly. Remove from heat and set aside.
In the same skillet, add the ground chuck and chopped white onion. Season with salt and black pepper to taste. Cook until the meat is browned and the onions are soft. Drain any excess fat and stir in the can of diced green chilies.
Heat some vegetable oil in a frying pan over medium heat. Fry each flour tortilla until golden and crispy on both sides. On a baking sheet, spread a layer of the beef mixture on a tortilla, followed by a generous pour of the sauce, and top with a sprinkle of shredded cheddar cheese.
Preheat your oven to 375°F (190°C). Place the assembled pizzas in the oven for about 10 minutes or until the cheese is melted and bubbly.
Remove from the oven and drizzle with picante sauce to taste. Slice into wedges and serve hot, allowing everyone to enjoy this scrumptious dish!
