In a large microwavable bowl, add the butter. Microwave until just melted. Add the yogurt, milk, and eggs and whisk until smooth.
Add the flour, oats, baking powder, baking soda, and salt. Use a rubber spatula to stir/fold the batter together until just combined. If too thick, stir in a splash of milk. If too runny, stir in a bit more flour. If you let it sit for a few minutes, the batter will thicken up.
Scoop the batter into a preheated and buttered waffle iron (we do a heaping ⅓ cup per waffle).
Serve warm topped with whatever toppings you want!
The best way to reheat waffles is in your toaster or toaster oven.