Combine the butter, egg, sugar, vanilla, and mayo. In a tablespoon add the vinegar to the baking soda and mix. Add to the rest of the ingredients. Mix well. Add the flour and mix until flour is well incorporated.
Press the dough against the sides and bottom of the molds. Make sure there is no open area and that the thickness of the dough is the same everywhere for even baking Bake in a preheated oven to 365˚ F for about 20 minutes, until golden.
Allow mini tarts to cool and flip, the molds should come right off.
Melt the chocolate over a double boiler.
Place the walnuts into a food processor fitted with the chopping blade and pulse until well chopped. Place into a bowl. Once the tarts have cooled hold the tart with your fingers on the bottom turn over and dip into the chocolate. With a teaspoon fill the insides of the tart with chocolate and spread evenly.
Then dip tops of baskets into the walnuts. Set aside so the chocolate can set. Continue with remaining baskets.
With a mixer on medium speed, beat the cream cheese, rum and butter. Turn mixer down to low add half of the dulce de leche. Beat. Add remaining dulce de leche and mix. Turn off mixer and gently fold in the cool whip with a wooden spoon or spatula.
Use a decorating bag and add the cream to the tarts. (Or with a tablespoon add cream to the tarts. Then with a clean toothpick swirl the top to look as if you piped it with a bag.h easier.) Keep refrigerated or in cool temperature.