Preheat your oven to 350°F (175°C) and line your cookie sheets with parchment paper.

In a standing mixer, cream together the softened butter and sugar until they form a light and fluffy mixture.

Add the eggs one at a time, ensuring each is fully incorporated before moving onto the next.

Mix in the pure vanilla extract until evenly mixed.

In a large bowl, whisk together the flour, baking powder, baking soda, and cream of tartar until thoroughly combined.

Gradually introduce the dry ingredients into the wet mixture, stirring until fully combined.

Using a small ice cream scooper, portion out the dough and roll each piece into a ball. Set them aside on your cookie sheets.

Pour the Christmas sanding sugar into a bowl. Roll each dough ball in the sugar, then place them back on the sheets, leaving about 2-3 inches between each ball.

Gently flatten each dough ball into a thick disk using the palm of your hand.

Bake in your preheated oven for about 11-13 minutes, or until the edges are lightly browned.

Allow the cookies to cool completely before serving.