Beat 1 egg and 2 tablespoons of milk (or half and half) well with a fork. Set aside.

Heat oven to 400 degrees.

Combine 2 1/2 cups of the flour, baking powder and salt in a large bowl. Add the cheeses and toss gently with a fork until combined. Add the scallions and toss gently with a fork until combined.

Beat the milk (or half and half) with the egg and gently fold it into the dry ingredients, mixing lightly until a soft dough forms. Add up to 1/2 cup additional flour, if the dough is too sticky.

On a floured surface, gently pat the dough into a circle approximately 1-inch thick (or into two smaller circles for 12 scones) The key to tender scones is to handle the dough as little as possible and with a light touch. Cut the circle(s)into 8 or 12 wedges and place them on a heavy duty baking sheet lined with parchment paper.

Brush the tops and sides of the scones with the egg wash. Bake for 20 to 25 minutes, or until golden brown. Cool on a wire rack. Serve warm or cool completely and refrigerate or freeze in a heavy zipper bag or airtight container.