Prepare the Dough
In a bowl, whisk flour, baking powder, salt, and cinnamon.
In a separate bowl, cream butter and sugar until light and fluffy.
Add egg and vanilla; mix until combined.
Gradually add dry ingredients and mix until a soft dough forms.
Chill the Dough
Divide dough into two discs.
Wrap in plastic wrap and chill for 30–45 minutes.
Chilling helps the cookies hold their shape when baking.
Roll & Cut
Preheat oven to 350°F (175°C).
Roll dough on a lightly floured surface to ¼-inch thickness.
Use heart-shaped cookie cutters to cut cookies.
Place cookies on a parchment-lined baking sheet.
Decorate
Press cinnamon heart candies gently into the dough.
Sprinkle lightly with cinnamon sugar or sanding sugar if desired.
Bake
Bake for 8–10 minutes, until edges are set but centers are soft.
Cool on the baking sheet for 5 minutes, then transfer to a rack.