Combine filling ingredients in a saucepan and bring to a low boil over low-medium heat. Cover and allow to simmer until the contents reach the consistency of jam, then set aside to cool. Once cool, in a food processor or blender, blend filling until you reach a smooth, pasty consistency. Set aside.

For the cookie ingredients, melt the butter, allow to cool to just above room temperature, then combine with egg and vanilla. Once well-combined, add in flour and sugar. Wrap the dough in plastic wrap and chill for 30 minutes to an hour.

Flour your surface and roll out your dough until you achieve a thickness of 1/8 of an inch or less. Then, cut the dough into four-inch-wide rectangles (they can be as long as you want), and spread the filling about 1 inch thick in the center of these rectangles. Finally, fold the width of those rectangles over, and voila! You're ready to cut the newton rectangles into newtons!

Turn your filled-in newton rectangle thingies over and onto a piece of string. Finally, use the string to cut it into newtons by crisscrossing and pulling on each end of the string.

Once finished, place the newtons onto a greased or non-stick pan and bake for 15–20 minutes, or until lightly brown!