I first made my friend, Angella's, whipped shortbread six or seven years ago and it was added to my yearly Christmas baking schedule immediately. The recipe is wonderful as-is but over the years I've made a few tweaks. The orange zest makes it taste more Christmassy (if that's even possible) and if you're feeling fancy you can drizzle on some dark chocolate for extra punch.
One quick note about this recipe: a stand mixer is a must. You can try to use an electric hand mixer in a pinch but be prepared for a tired arm.
Whipped Orange Shortbread
Makes 5-1/2 dozen
1 lb unsalted butter, softened
3 cups all-purpose flour
1 cup icing sugar
1/2 cup cornstarch
1/2 teaspoon salt
zest of 1 orange, finely grated
Preheat oven to 325F.
Add remaining ingredients. Whip for at least 10 minutes, pushing the batter down the sides of the bowl every few minutes so everything gets good and whipped. You'll notice the batter starts to look lighter (both in colour and texture) as you whip.
Spoon by tablespoon onto parchment paper-lined cookie sheets and bake for 20 minutes. The cookies should be barely golden on the bottom.