• Using a countertop mixer, cream together the butter and sugar until light and fluffy (2-3 minutes on medium speed).
• Add the egg and vanilla; stir until well combined.
• In a separate bowl, add the flour, baking soda and salt; stir until well combined.
• Add half of the dry ingredients to the butter mixture followed by half of the buttermilk, stirring between each addition. Repeat with the remaining dry ingredients and remaining buttermilk.
• Cover and chill dough for at least 1 hour.
• Preheat oven to 375°F.
• Remove ¼ of the dough and place on a well-floured countertop. Leave the remaining dough in the refrigerator.
• Using a well-floured rolling pin, roll the dough out to as thin as possible (~1/8"). (Tip: If you have a pasta machine, you can roll the dough through the pasta rollers until very thin.)
• Use a cookie cutter to cut dough into desired shapes. (I prefer just a simple round cookie for this recipe, but feel free to experiment! Also, if dough warms up too much and begins to stick, just place it back in the refrigerator for a few minutes.)
• Place cookies on a parchment-lined baking sheet and sprinkle tops of cookies lightly with superfine sugar.
• Bake at 375°F for 8-9 minutes, or until edges of cookies just begin to turn brown.
• Repeat with remaining dough.

For the Eggnog Ice Cream Sandwiches

• Let the Eggnog Ice Cream rest at room temperature for a couple of minutes, or until soft and spreadable.
• Spread 2-3 Tbsp of ice cream onto one of the sugar cookies. Top with another sugar cookie. Wrap the ice cream sandwich in plastic wrap. Repeat to make as many ice cream sandwiches as desired. (Note: You'll probably have ice cream and cookies left over, but that shouldn't be a problem, right?)
• Freeze the wrapped-ice cream sandwiches for 2 hours, or until ice cream has hardened. Garnish tops with a dash of cinnamon before serving.