The cookies. Preheat oven to 350°F (175°C). Line a baking sheet with parchment paper. Set aside.

In a large bowl, beat together the sugar, vanilla, lemon zest and butter with an electric mixer until well blended. Beat in eggs, one at a time. After adding all the eggs, beat for 1 minute more. Stir in baking powder and flour and blend just until mixed. Cover the dough and refrigerate for about 1 hour. The dough will be sticky, so we chill it to make it easier to handle.

To form the knots, roll the dough into logs, about 5 inches long. Take one side and spiral the log into a circle. Repeat until all the dough is used. Bake for 15-17 minutes or until light golden brown.

The icing. Melt the butter over low heat. Add the sugar, lemon juice, and water. Whisk until the sugar melts. If icing is too thick, add some more water.

Remove cookies from the oven and let them cool. Brush the icing over the cookies. If using, top with colored sprinkles. Let the cookies to dry for about an hour. Store in an airtight container. Enjoy!