Prepare the Dough

1. Cream Butter and Sugar: In a mixing bowl, beat the softened butter and caster sugar together with an electric mixer until light and fluffy.
2. Add Egg Yolk and Vanilla: Mix in the egg yolk and vanilla extract until fully incorporated.
3. Combine Dry Ingredients: Gradually sift in the flour (and optional spices) and mix until the dough comes together. Avoid overmixing.
4. Chill the Dough: Shape the dough into a disc, wrap it in plastic wrap, and chill in the refrigerator for 20-30 minutes.

Roll and Cut the Biscuits

5. Preheat the Oven: Preheat your oven to 350°F (180°C). Line baking sheets with parchment paper.
6. Roll Out the Dough: On a lightly floured surface, roll out the chilled dough to about ¼-inch thickness.
7. Cut Shapes: Use festive cookie cutters to cut out shapes. Re-roll the scraps and cut more shapes as needed.
8. Transfer to Baking Sheets: Place the biscuits on the prepared baking sheets, spacing them slightly apart.

Bake the Biscuits

9. Bake: Bake in the preheated oven for 10-12 minutes, or until the edges are lightly golden.
10. Cool: Allow the biscuits to cool on the baking sheets for 5 minutes, then transfer to a wire rack to cool completely.

Decorate the Biscuits

11. Prepare Icing (Optional): Mix powdered sugar with a few drops of water or lemon juice to create a thick icing. Add food coloring if desired.
12. Decorate: Use icing bags or squeeze bottles to decorate the biscuits. Add sprinkles or edible glitter while the icing is still wet.
13. Let Set: Allow the decorations to set before stacking or storing the biscuits.