Pour water into a medium sauté pan to a level about 1 1/2 inches deep. Bring the water to a boil over high heat. Add the chicken (it should be covered by about 1/2 inch water) and reduce the heat to medium. Cover and cook for about 8 to 10 minutes or until just cooked through. (Otherwise, microwave on High for 6 minutes, turning halfway to promote even cooking.) Drain and discard the cooking liquid. Transfer the chicken to a plate. When it is cool enough to handle, cut into 3/4-inch pieces.

Melt the butter in a large saucepan over medium-high heat. Add the onion; cook, stirring occasionally, for 2 minutes or until tender. Stir in the reserved vegetable liquid, the remaining filling ingredients, and the cooked chicken. Cook, stirring frequently, until hot.

For the biscuit topping, stir together the flour, sugar, baking powder, and salt in a medium bowl. Cut in the butter using a pastry blender or two forks, until the mixture resembles coarse crumbs.