Bake cupcakes according to package directions.
While the cupcakes are baking, make your frosting. For the vanilla buttercream, beat the softened butter and vanilla together, then add the powdered sugar and salt. Slowly add enough milk until it's the right consistency. For the chocolate butter cream, whisk the powdered sugar and cocoa in a bowl. In a separate bowl, beat the softened butter and vanilla. Add the cocoa/powdered sugar mixture and salt. Slowly add enough milk until it's the right consistency. Start with 2 tablespoons and add more if necessary.
When the cupcakes are done and cooled completely, frost half with vanilla frosting, and half with chocolate frosting.
For the eyes, separate your sandwich cookies in half, so that the white middle stays on one side of the cookie. If there are any little chocolate or vanilla cookie bits, use a paring knife to gently scrape them off. Place two cookies (frosted half of the cookie) side-by-side on the cupcake. Dab a little frosting onto two brown candy pieces and place them on the cookies. Place an orange or yellow candy piece right under the cookies for the nose. (I like using a yellow one on the vanilla, and orange one on the chocolate.) For the cute little ears, cut the unfrosted cookie halves into quarters, then place them above the eyes.