Preheat the oven to 350 degrees F. Line 4 mini cupcake pans with 96 cupcake liners.
Chop the raisins and place in a bowl. Add the baking soda, and then stir in the boiling water. Let stand for 30 minutes.
Add the flour, cinnamon, and salt to a bowl. Cream the butter in a large bowl with an electric mixer on medium speed. Gradually add the sugar, mixing until light and fluffy. Add the eggs and egg yolks, 1 at a time, mixing after each addition, and beat until light and fluffy. Add the lemon juice, vanilla extract, rum flavoring, and rum. Add the flour mixture alternating with the raisin mixture, beginning and ending with the flour mixture. Pour into the cupcake liners and bake until light brown on top, 12 to 13 minutes. Cool before frosting.
Cream the butter in a large bowl with an electric mixer on medium speed. Add the vanilla and salt. Alternate adding the powdered sugar with the cream, a teaspoon at a time, until the desired consistency is reached.
This recipe was provided by a chef, restaurant or culinary professional. It has not been tested for home use.