Preheat the oven to 350°F. Line a baking sheet with parchment paper.
Place the lemon zest and granulated sugar in a medium bowl. Beat until the zest releases its oils, about 2 minutes.
Add the butter, beat until combined, about 2 minutes.
Add the eggs and vanilla, beat until combined, about 1 minute.
Whisk together the flour, baking powder, salt, and cardamom. Add to the bowl, mix until a dough forms.
Divide the dough in half. Create two rectangular logs, about 9.5 inches long and 2.5 inches wide. Bake for 25-30 minutes or until a toothpick comes out clean. Reduce the oven temperature to 325°F.
Let the logs cool, using a serrated knife cut about 1 inch slices( see photos in post for reference) Place on a rack cut side up. Bake again for 15-20 minutes or until desired crunchiness. Let cool before dipping in white chocolate.
Dip the flat bottom in melted white chocolate, place on a parchment lined plate. Place in the refrigerator until set. Take out and enjoy!