Preheat the oven to 350 degrees F (175 degrees C). Grease a 2-quart baking dish.
Arrange peaches, apples, pears, blueberries, cherries, and plums in the prepared baking dish.
Whisk sugar, milk, and egg together in a bowl until smooth. Sift flour, baking powder, and salt together into a separate bowl; stir into sugar mixture until combined. Stir in melted butter and vanilla extract until incorporated; pour batter over fruit to cover.
Bake in the preheated oven until bubbly and lightly browned on top, about 30 minutes. Serve warm.