Line an 8-inch cake pan with lightly-buttered plastic wrap. Place the blueberries in the pan. In the bowl of a food processor, place the flours, whole wheat flour, baking powder, baking soda, salt, and brown sugar. Pulse a few times to combine. Cut the cold butter into 1/2-inch cubes. Pulse them with the dry ingredients in the food processor until the largest pieces of butter are the size of small peas. Transfer the mixture to a bowl. Toss in the oats lightly with a spatula. Add the half and half and the starter and mix lightly with your hands until just barely incorporated. Press the dough into the pan over the berries. Cover the top of the pan with plastic wrap and freeze overnight, or for at least four hours. Unmold the frozen scone round. Use a sturdy knife to cut the round into 8 wedges. Transfer the scones to a buttered or parchment-lined baking sheet. Let them stand until slightly thawed, about 30 minutes. Meanwhile, preheat the oven to 400F. Make an egg wash by beating the egg together with a splash of water and a pinch of salt. Just before baking, brush the tops and sides of the scones lightly with the egg wash. Bake for about 30 minutes, or until the scones are set and lightly browned. Enjoy while warm!