Add all ingredients to a food processor or blender and process until a paste is formed and no large chunks are left.

Place in a bowl and cover with plastic wrap.

Place in the fridge to chill for at least an hour but preferably overnight so ingredients can meld together.

In a large mixing bowl cream butter with an electric mixer until light and fluffy.

Add both sugars and baking soda and mix to combine.

Add egg, vanilla and salt and blend together, scraping sides of bowl with spatula.

Add the flour in four batches mixing well between each addition.

Once incorporated remove dough to a cutting board. Cut into two halves.

Flatten each half and wrap in plastic wrap then place in the fridge to chill for at least 3 hours- overnight.

Sift confectioner sugar into a medium mixing bowl.

Add 3 teaspoons of lemon juice and whisk together. Add more lemon juice a teaspoon at a time as needed until desired consistency is achieved.

Preheat oven to 375 Degrees F. Line 2 baking sheets with parchment paper.

Remove chilled dough and filling from the fridge. Let dough rest for 10-15 minutes.

Place a 14 x 10 inch piece of wax paper on a cutting board. Lightly dust with flour.

Unwrap one piece of dough and roll into an 8x10 inch rectangle.

Cut in half so that you have (2) 4x10 strips.

Split your filling into 4 equal portions and fill the center of each strip of dough from end to the other the long way.

Use your wax paper as a guide to help lift the dough to wrap around the filling.

Pinch the edges together to seal and make a seam. then pinch the ends together to enclose the filling completely.

Place on your lined baking sheet seam side down then repeat with remaining dough and filling.

Place in preheated oven on center rack. Bake for 13-15 minutes or until edges are slightly browned.

Remove from oven and cut in 1 inch slices at an angle.

Place each slice on a cooling rack and cool completely.

Drizzle tops of cooled cookies with icing and sprinkle with nonpareils.