Citrus Peel Cookies

Combine room-temperature butter with white and brown sugar, mixing with a fork for 1-2 minutes until smooth. Add the room-temperature egg and mix with a fork for 1 minute until well incorporated.

In a separate bowl, whisk together the dry ingredients: flour, baking powder, salt, and vanillin. Add this dry mixture to the wet ingredients. Mix with a fork for 1 minute, then knead the dough by hand until it comes together into a cohesive ball.

Fold in the diced candied orange or lemon peel, incorporating it into the dough for 30 seconds. Divide the dough into portions, shape them into balls, place them on a parchment-lined baking sheet, and gently flatten the tops with your fingers.