Preheat the oven to 350 degrees F. Line mini cupcake pans with cupcake liners.
together the flour, baking powder, and salt. Set aside. In a large bowl, cream together the butter and sugar until light and fluffy. Beat in the eggs and yolks, 1 at a time, and then stir in the grapefruit
oil and grapefruit zest
. Stir in the vegetable oil
. Fold in the flour mixture, alternating with the grapefruit juice.
Fill the cupcake liners about two-thirds full. Put in a piece of Guava Truffle Cookie in each cup. Bake until a toothpick inserted into the center of the cakes
comes out clean, 9 to 12 minutes. Cool completely, and then frost with Rosewater Frosting