In a large mixing bowl, whisk together the all-purpose flour, granulated sugar, baking powder, salt, and orange zest until evenly combined.
In a separate bowl, whisk the lightly beaten eggs, melted butter, and the selected liqueur until smooth. Add the wet mixture to the dry ingredients and mix with a spoon or spatula until the dough begins to form.
Turn the dough onto a lightly floured work surface and knead gently until it becomes smooth and cohesive. Shape the dough into a ball, wrap it in plastic wrap, and allow it to rest at room temperature for 30 minutes.