Zest all citrus fruits and set aside 2 teaspoons of zest in a small bowl. Mix the zest with 1/2 cup of sugar and set aside.

In a mixing bowl, beat the softened butter and remaining 1 cup sugar for 1-2 minutes. Add the egg and beat until combined.

Add flour, baking powder, baking soda, and the zest mixture to the bowl. Mix until just combined.

Preheat oven to 350°F. Line baking sheets with parchment paper.

Shape dough into 3/4 to 1-inch balls, then roll in the remaining sugar/zest mixture to coat.

Place balls on prepared baking sheet and gently flatten with the bottom of a glass. Optionally, sprinkle additional sugar on top.

Bake for 10-12 minutes until edges are golden brown. Remove from oven and cool on wire racks.

Store in an airtight container for up to a week. Enjoy!