Preheat the oven to 400? F. Line a baking sheet with parchment paper or a silicone baking mat
In a food processor*, combine the lemon zest, flour, ½ cup of sugar, baking powder and salt. Pulse briefly to blend. Add in the cold butter pieces and pulse again briefly until the mixture resembles coarse meal and the butter pieces are no larger than peas. Transfer to a medium mixing bowl.
In a small bowl, toss together the chopped cranberries and remaining 3 tablespoons sugar. Stir this into the flour-butter mixture.
In another small bowl or a liquid measuring cup, combine the egg, egg yolk and heavy cream; whisk to blend. Add the liquid ingredients to the bowl with the dry ingredients and stir gently with a spatula or wooden spoon just until all the dry ingredients are moistened. Knead gently to be sure the dough is evenly mixed, being careful not to overwork the dough
Place a 2½- or 3-inch round biscuit cutter on the lined baking sheet. Scoop some of the dough inside the cutter and pat down gently to form a 1-inch thick round. Repeat with the remaining dough, placing the rounds 2-3 inches apart on the baking sheet.** Sprinkle lightly with additional sugar.
(To freeze before baking, flash freeze at this point. Place the baking sheet with the shaped scones into the freezer and chill until frozen. Transfer to a freezer-safe plastic bag and store until ready to bake.)
Bake in the preheated oven until light golden brown, about 15-20 minutes. (If baking from the freezer, add approximately 5 minutes to the original baking time.)
*Note: A food processor is not required for this recipe. You can achieve the same result using a stand mixer, a pastry blender, or even just two knives. I like the food processor because it is quick and easy, but all methods work equally well.