Preheat oven to 350 F. Grease a 6 1/2-inch cast iron skillet with butter. In a small bowl, toss the oats with cinnamon, sugar and olive oil. Put the fruit in the skillet and top with the oat mixture. Bake 35 minutes until fruit is bubbly and oats are golden. Let cool for 5-10 minutes. Top with a scoop of vanilla frozen yogurt, if desired.