In a medium bowl, mix 1 cup of the flour with 3 tablespoons of the sugar and the baking powder. Add the butter and, using your fingertips, rub the butter cubes into the flour until it resembles coarse meal. Add the egg and cream and mix to combine the ingredients evenly and form a soft dough.
In a 10-inch cast-iron skillet, combine the blueberries, remaining 3⁄4 cup sugar and 2 tablespoons flour, the orange zest, and the mace.
Stir to coat the berries. Pour in the orange juice and set over medium- low heat. Bring the fruit to a boil, reduce the heat, and simmer for 2 minutes to thicken the mixture and cook the flour. Remove the skillet from the heat. Drop rounded tablespoons of the biscuit dough onto the fruit, leaving a little space in between. There should be 12 to 16 biscuits.
Place the skillet in the oven and bake for 16 minutes, or until the biscuits are lightly browned on top. Remove from the oven and let stand for 15 to 20 minutes. Serve warm, with a scoop of ice cream, if desired.