In a bowl, combine flour, 1 cup sugar, baking powder, salt and butter. Mix it all together using your clean hands until the mixture resembles walnut size pieces. Add the water, stir together with a spoon until moistened. Set it aside.
Preheat oven to 350°Wash the blueberries thoroughly. In a bowl, combine 1/2 cup of sugar, blueberries, and juice of 1/2 lemon. Stir everything together then set aside.Place the contents of the fruit cups in a pot, add lemon juice, 1/2 sugar, and 1/4 cup of water. Let that boil. Add the water and cornstarch mixture into peaches. Stir and cook for another 30 seconds.
Transfer the fruit into a baking pan. Try to take some of the liquid out with a spoon if necessary.
Spoon the cobbler topping on top. Place the pan into a foil-covered sheet pan. Bake it in the oven for 1 hour.