PREPARE DULCE DE LECHE:Heat soy milk over medium heat until it comes to a simmer. Whisk in all other dulce de leche ingredients. Continue to simmer for 30 minutes or until caramel like consistency is achieved.Remove from heat and set aside. keep warm.
Prepare cookies: Preheat oven to 375 degrees. Line cookie sheets with parchment paper. Stir flour and cinnamon into a medium sized mixing bowl. Mix in Both brown and regular splenda.
Rub margarine or butter in flour mixture until crumbly. Add soy milk and mix until mixture forms dough. Roll dough out onto a floured surface to 1/8 inch thick. Cut dough into 2-inch wide circles using a cookie cutter.
Place rounds on an ungreased cookie sheet lined with parchment paper. Bake for 20 minutes or until lightly golden brown on edges. Allow cookies to cool for 3 minutes.
Spread each cookie with 1 tablespoon of Dulce de Leche. Sandwich 2 cookies together. serve warm. I like them cool.