In a sauce pan over medium high heat, melt butter, continuously stirring until turns a medium brown color and smells fragrant. Set aside.

In a large mixing bowl beat eggs, add brown sugar; mix well.

Add greek yogurt and browned butter; mix well.

Add rum extract, eggnog, soda powder; mix well.

Add flour 1 cup at a time and mix just until incorporated. (Don't over mix)

Cover with wax paper and refrigerate at least 1 hour.

Preheat oven to 325 degrees.

Place 1 inch (a small cookie scoop works well) rolled cookie dough on un-greased cookie sheet, 2 inches apart. Press with the bottom of a cooking sprayed glass until 1/4 inch thick.

Bake 13-15 minutes until bottoms are very lightly browned. Remove to rack to cool.

In a medium mixing bowl beat butter until smooth.

Add rum extract, nutmeg, and cinnamon; mix well.

Add 1 C powdered sugar; mix in.

Alternate remaining powdered sugar 1 C at a time with 1 Tbsp Eggnog; mix until incorporated.

Frost cookies, add additional nutmeg for dusting. (I used a Wilton 20 tip and starting on the outer edge swirling to the center.)