In a large bowl, beat softened butter and sugar until light and fluffy (2-3 mins).
Mix in the egg and vanilla until combined.
Whisk flour, baking powder, and salt in a separate bowl. Gradually add to the wet mix until a dough forms.
Divide dough into 2 discs, wrap in plastic, and refrigerate for 1 hour (or freeze for 20 mins).
Preheat oven to 350°F (175°C). Roll dough to ¼-inch thickness on a floured surface. Cut into shapes.
Place cookies on parchment-lined baking sheets. Bake for 8-10 mins until edges are lightly golden.
Let cool on a wire rack before decorating with icing or sprinkles.
