For biscuit topping:

Preheat oven to 400° F. Grease a 8-inch round cake pan, then set aside.

In a medium mixing bowl, stir together flour, sugar, baking powder and salt. Cut in butter until mixture resembles coarse crumbs. Make a well in the center; set aside.

In a small bowl, use a fork to beat together egg and milk. Add to dry topping mixture all at once and stir until combined.

For filling:

In a medium saucepan, combine sugar and corn starch. Add cherries and water. Cook and stir until slightly thick and bubbly. Stir in butter. Reduce heat to keep hot.

Transfer hot filling to cake pan. Immediately spoon biscuit topping on top of filling.

Bake in a 400° F. oven for 20 to 25 minutes or until a toothpick inserted into the topping comes out clean. Serve warm.