FOR THE FILLING:
A slump is a fruit dessert made in a skillet and topped with sweet biscuits. It's a variation on cobbler (which is often cooked in a baking dish). Meanwhile, a grunt is a slump cooked in a covered pot on the stove so that the steam cooks the biscuits.
Note: You can substitute any fruit, as long as the total volume is 6 cups. If your fruit is particularly juicy, reduce the water by ½ cup.
Preheat oven to 400°. Toss fruit with brown sugar, flour, juice, and ginger. Pour into a 10- to 12-inch cast-iron pan. Put in oven for about 15 minutes.
FOR THE TOPPING
Meanwhile, make the biscuit dough: In a large bowl, whisk together flour, oats, baking powder, cinnamon, and sugar. Add beaten egg, milk, and melted butter, stirring just until moist. Don't overmix.
Remove fruit from oven and drop dough onto fruit, forming about 8 mounds. Sprinkle with cinnamon sugar. Bake until biscuits are lightly browned and juices are bubbling, 15 to 20 minutes.