If desired, top each cupcake with half of a key lime slice. Add the key lime zest and 3 tablespoons of the key lime juice, mixing well and adding additional key lime juice as needed to reach a good piping consistency. A citrus dessert is the best kind of dessert when it’s hot outside. Sprinkle cupcakes with additional key lime zest and Graham Crumble. Transfer the frosting to a piping bag with a decorative tip and pipe the frosting onto the cupcakes. Add Rating & Review. Advertisement. Key Lime Cupcakes have all the flavors of key lime pie in a pretty little cupcake. Serve immediately or chill for up to 3 days . 14 Ratings. Reviews. Bright and fresh lime flavor that’s a little tart, a little sweet, that makes for a bright summery dessert.