Preheat oven to 425 and line a cookie sheet with parchment paper. Set aside. 

In a large bowl, combine bisquick and sugar and mix well.

Add butter and use a pastry blender to blend the cold butter into the dry mixture until crumbly.

Zest two lemons and fold zest into the dry mixture. 

In a separate, smaller bowl, whisk yogurt, egg and juice of 2 lemons well. Stir into dry ingredients until combined. 

Sprinkle bisquick onto the parchment paper and on your hands. Divide the dough in half and spread the batter into 2 rounds, about 8" in diameter and 1/2" thick. 

Use the knife to score each round in six triangles.

Brush the top of the dough with milk and a pastry brush, sprinkle with coarse sugar. 

Bake for 18-20 minutes or until scones begin to brown.

Remove from oven and let stand 2 minutes before cutting the scones apart on the score lines.

Let stand to cool before glazing.

Mix together powdered sugar and milk or lemon juice until mixture is smooth and not overly runny.

Place glaze in a sealable sandwich bag and seal shut. Snip the tip of the bag and drizzle glaze on top of each scone.

Let stand for glaze to harden before serving.