Prepare the Dry Ingredients: In a medium bowl, whisk together flour, salt, and baking powder. Set aside.
Cream the Butter and Sugar: In a large bowl, beat softened butter and sugar together until light and fluffy (about 2–3 minutes).
Add Wet Ingredients: Beat in the egg, milk, lemon juice, and vanilla extract until fully combined.
Combine and Chill: Gradually mix in the dry ingredients until a soft dough forms. Wrap the dough in plastic wrap and chill for at least 30 minutes to firm up.
Roll and Cut: Preheat oven to 350°F (175°C). On a floured surface, roll dough to about ¼-inch thickness. Cut into desired fall shapes (leaves, pumpkins, acorns, etc.).
Bake: Place cookies on a parchment-lined baking sheet and bake for 8–10 minutes, or until edges are just turning golden.
Cool and Decorate: Cool completely before frosting or decorating with royal icing, buttercream, or edible gold leaf.