Preheat oven to 375F. Melt butter in a 10-12 inch cast iron, (or heavy ovenproof), skillet over low heat. Add 3/4 c. sugar & 1/4 c. molasses to pan & stir. Place fruit in pan trying not to leave large spaces. Cook over low heat while you prepare the cake.
Cake: beat 1 stick butter & 2/3 c. sugar until light & fluffy. Mix in vanilla & eggs. Combine flour & baking powder, salt & cinnamon, then add alternately with yogurt to the butter/sugar mixture , until well blended. Spoon batter to cover fruit. Bake at 375F. for 25-35 minutes depending on pan size. Look for it to bubble & be light tan. Wait 5 minutes & invert to serving platter. I used a foil lined pizza pan. Serves 10.