Preheat oven to 425 F and brush large baking sheet with oil. Set aside.
To make taco filling, preheat large non-stick skillet on medium-high heat and add ground beef. Cook for 5 minutes, constantly breaking into small pieces and stirring. Drain the fat. Then add garlic powder, onion powder, taco seasoning, green chilies and cook for another 3-4 minutes, stirring a few times. Turn off heat.
Place tortillas on a large plate, cover with damp towel and microwave for 30-60 seconds or until softened.
Lay out tortillas on greased baking sheet. Spread some refried beans on half of each, top with some taco meat and then some cheese. Fold over to seal, pressing on it and repeat with remaining ingredients, working in batches. Spray or brush with a bit more oil and place another baking sheet on top. You might have some leftover ingredients that you can serve.
Bake for 15-18 minutes or until tacos are crispy, removing the top sheet at 12-15 minute mark. Remove from the oven, transfer to a large platter and repeat with remaining tacos. If you have 4 baking sheets, you can bake both at same time otherwise you have to work in batches.
Serve warm with salsa, guacamole and yogurt, and your other favorite toppings.