1-First Step: Whisk dry ingredients. In a medium bowl, combine 2 1/4 cups all-purpose flour, 1 teaspoon baking powder, and 1/2 teaspoon salt. This ensures even distribution for uniform cookies. For gluten-free, use the substitute here.

2-Second Step: Cream butter and sugar. Beat 1 cup softened unsalted butter and 1 1/2 cups granulated sugar on medium speed for 3 minutes until light and fluffy. Scrape bowl sides for smooth mix. Vegan option: use coconut oil.

3-Third Step: Add wet ingredients. Mix in 1 large egg and 2 teaspoons vanilla extract until fully combined, about 1 minute. For low-calorie, reduce sugar slightly in this stage.

4-Fourth Step: Incorporate dry mix. Gradually add the flour mixture to the wet ingredients on low speed. Stop mixing once a soft dough forms; do not overmix to keep cookies tender.

5-Fifth Step: Chill the dough. Divide dough in half, flatten into disks, wrap in plastic, and refrigerate for at least 1 hour or overnight. Chilling prevents spreading for crisp cutout cookies.

6-Sixth Step: Preheat oven to 350°F (175°C). Line baking sheets with parchment paper. Roll dough to 1/4-inch thickness on a floured surface. Use Christmas cookie cutters for shapes like stars or gingerbread men.

7-Seventh Step: Bake cookies. Place cutouts 2 inches apart on sheets. Bake 8-10 minutes until edges are lightly golden. Cool on sheets for 5 minutes, then transfer to wire racks.

8-Eighth Step: Prepare royal icing. Whisk 3 cups powdered sugar, 2 tablespoons meringue powder, 1/4 cup water, and 1 teaspoon vanilla until stiff peaks form, 5-7 minutes. Thin with water drops for flooding.

9-Final Step: Decorate and serve. Pipe icing outlines, flood centers, add sprinkles. Let dry 1-2 hours. Store or gift these decorated Christmas sugar cookies. Pairs well with milk or tea.