Preheat oven to 400 degrees F and lightly grease a baking sheet.If using frozen berries, defrost before baking. The recipe might still work with fully frozen berries but I haven't tested it out yet. So defrost 'em or simply grab a carton of fresh berries!In a large mixing bowl, stir together dry ingredients: flour, sugar, baking powder, baking soda, and salt.Cut in the butter with a pastry cutter. I don't own one so I minced the chilled butter into small cubes and then cut into the flour mixture using a pair of sharp knives. You can also easily grate the butter into the flour using a box/cheese grater.Add your orange zest.In a separate bowl, whisk together your egg, milk, yogurt and vanilla.Use a fork to move the flour mixture to the sides of the bowl, making a hole in the middle, then pour the egg mixture into the center.Stir until just moistened, then carefully fold/knead in blueberries. Some will remain whole and some may smush into oblivion, blueberries have a mind of their own. At this point the mixture will probably seems fairly dry, which is absolutely what we're going for here! If needed, add a tablespoon of milk to moisten and knead for 3-4 strokes in the bowl.Grab a sheet of parchment paper and lightly sprinkle with flour to prevent sticking.Gently knead your dough until smooth, trying not to exceed 12-15 total strokes if possible. Shape into a 7 inch circle on your baking sheet and cut into wedges.Glazing pre-baking will give you a crusty-crunchy-sweet outer layer to your scones. If you prefer them softer on top add the glaze after baking. Or you can go nuts and add some before and a little extra after. I might be guilty of the latter. Love it so.If you've decided to add your glaze prior to baking, add a light drizzle to the scones and sprinkle each with a teeny bit of sugar.Bake at 400F for 15-20 minutes, until golden, using a toothpick to test the center.Move to a wire rack to cool and enjoy! They're fabulous straight from the oven or cooled to room temperature.In case you actually wind up with leftovers, wrap tightly with saran wrap and store at room temperature for up to four days. They're great for grab-and-go breakfasts and snacks!