In large bowl, beat together butter and sugar with electric mixer on medium speed until light and fluffy, about 3 minutes. Add eggs, one at a time, mixing well after each addition. Add eggnog, rum (optional) and vanilla.

Combine flour, baking powder, nutmeg and salt. Add to butter mixture, beating just until combined. Chill dough 30 minutes or longer for easier handling.

Heat oven to 350 F.

Roll dough out on a lightly floured surface to 1/4-inch thickness. If dough seems sticky, use additional flour and knead into dough. Using floured cookie cutters or a round biscuit cutter, cut into desired shapes.

Place on parchment lined cookie sheets, and bake 10 minutes or until edges are golden brown. Transfer to wire cooling racks; cool completely.

While your cookies are cooling, mix together the optional icing. Combine powdered sugar and butter in a small bowl, blending with a fork.

Add eggnog to the mixture and blend well. If icing is stiff, add additional eggnog 1 teaspoon at a time until a creamy frosting is achieved.

Spread on cooled Eggnog Cookies or other seasonal dessert. Sprinkle with nutmeg, if desired.