Preheat oven to 400 degrees F (200 degrees C). Spray a baking sheet with cooking spray.
Mix flour, 1/4 cup sugar, baking powder, and salt in a bowl. Add butter and mix with fingers until coarse crumbs form. Gently mix yogurt, egg, and vanilla extract into flour mixture until dough is just combined.
Turn the dough out onto a lightly floured surface and knead briefly, for five or six turns. Pat or roll the dough out into a 1-inch thick round. Cut into 8 wedges and place onto the prepared baking sheet. Brush each wedge with milk and sprinkle with remaining 1 tablespoon sugar.
Bake in the preheated oven until lightly browned, about 15 minutes. Serve warm or cool completely and store in an airtight container.
