Preheat oven to 350℉. Line a baking sheet with a split mat or parchment paper.
Prepare the apples: Melt the butter in a small saucepan over medium heat. Add the apples, stir and cook 4 to 5 minutes or until apples are softened. Stir in the cinnamon and set aside to cool.
Prepare the scone dough: In the bowl of a food processor, combine flour, sugar, baking powder, and baking sugar. Add the butter and mix again until coarse crumbs form. Transfer to a large bowl and stir in yogurt and apples until late dough comes together. You may need to use your hands. Turn the dough out onto a lightly floured surface and hand form a circle that is 1" thick. Using a sharp knife cut 8 wedges of equal size and place them about 1 inch apart on the prepared baking sheet.
Bake scones 15 to 17 minutes or until they are cooked through. Let cool 5 minutes on baking sheet and remove to a wire rack to cool.
Glaze the scones: In a small saucepan heat the butter until melted. Stir in the brown sugar and milk. Cook over medium-low heat for 1 minute. Transfer to mixing bowl and cool mixture slightly. Stir in the vanilla and 1/2 cup powdered sugar. Beat with an electric mixer until well blended. If necessary add up to 1/4 cup more powdered sugar for desired drizzling consistency. Drizzle over warm scones. Sprinkle with coarse or flaked sea salt.
Serve.