Preheat the oven to 350 degrees.
Place the greek yogurt on the counter so it comes to room temperature as you’re preparing the meat. (This will prevent the yogurt from curdling while it bakes!)
Heat a skillet on medium-high heat. Add the olive oil and onions to the skillet. Cook for about 5 minutes.
Add the ground beef and taco seasoning. Cook on medium heat until the meat is cooked through (not pink).
Drain excess grease from the skillet.
Use cooking spray to grease the casserole dish.
Spread the refried beans in an even layer on the bottom of the casserole dish. Next, add the layer of greek yogurt over the refried beans. The layer of ground beef will be next.
Sprinkle the cheese across the top.
Bake for about 10-15 mins, or until cheese is melted.
Add the toppings after the dish is finished baking.
Let the dish cool & enjoy!