Gently grease muffin tins or line them with muffin cups.
In a medium bowl, mix together the flour, sugar, baking powder, nutmeg and cinnamon.
In a separate bowl, beat together the Greek yogurt, egg nog, vanilla and melted butter.
Add the wet ingredients to dry and stir to combine.
Pour batter into prepared muffin tins and bake for 25 minutes or until toothpick placed in the center of muffin comes out dry.
Allow to cool in muffin tins for a few minutes before placing on a wire rack.
Prepare glaze by mixing powdered sugar and Greek yogurt in a small bowl until smooth.
Pour glaze on top of each muffin. Gently sprinkle with nutmeg.
Store in an airtight container in the refrigerator for 3-4 days.
Notes
To store in the refrigerator: Place cooled and glazed muffins in an airtight container and store in the refrigerator for up to 5 days.To store in the freezer: Place cooled and glazed muffins in an airtight container and store in the freezer for up to 3 months.