You'll make this budget-friendly dish again and again!
Preheat the oven to 180 °C. Grease 4 small ovenproof dishes (or 1 large dish) with nonstick spray.
1. Slice the sweet potatoes. Arrange a layer of sweet potato slices in each dish and scatter a little feta cheese on top. Arrange a few onion slices on top and repeat the layers until all the ingredients have been used, ending with a layer of onion rings.