1 cup plus 2 tablespoons all-purpose flour, measured correctly (spoon and sweetp/level method)
1 teaspoon baking powder
1/2 tsp ground cinnamon
1/4 tsp ground nutmeg
1/4 teaspoon salt
1/3 cup unsalted butter, softened at room temperature
1/4 cup granulated sugar
1/4 cup packed light-brown sugar
1 large egg yolk, room temperature
1 teaspoon vanilla extract
1/2 teaspoon rum extract (optional)
1/4 cup eggnog
1/4 cup butter, at room temperature
1 1/2 - 2 cups powdered sugar
1-2 tablespoons eggnog
1/4 teaspoon rum extract (optional)
1/4 teaspoon ground cinnamon (optional)
pinch of nutmeg (optional)
Preheat oven to 350 F. Line baking sheet with parchment paper or silicone mat. Set aside.
In a large bowl, whisk together the flour, baking powder, cinnamon, nutmeg and salt. Set aside.
Using a hand mixer or a stand mixer, cream butter and sugars together for about 3 minutes, until light and fluffy. Beat in egg yolk, vanilla, rum extract and eggnog, until combined.
Turn mixer to low and slowly add the dry ingredients, until just combined. Scoop about 1 1/2 tablespoonful and drop onto prepared baking sheet 2-inches apart.
Bake in preheated oven for 10 - 12 minutes. Allow to cool on baking sheet for 5 minutes then transfer to a wire rack to cool completely. The cookies will continue to cook while cooling. Spread with frosting and top with festive sprinkles.
To make the frosting:
Using a stand mixer or a hand mixer, cream butter for about 3 minutes, until light and fluffy. Slowly add powdered sugar and beat until combined. Add rum extract (if using) and eggnog, one tablespoon at a time until desired consistency or flavor is reached. Taste and add cinnamon, nutmeg and rum extract, if desired. Beat for an addition two minutes smooth. Frost cooled cookies and add sprinkles if desired.