paddle, beat butter until smooth. Add sugar and beat till light and fluffy. Add the eggs, mixing after each. Then add the lime juice and zest. The batter may look somewhat curdly and that's okay. Alternate adding the flour mixture and the buttermilk, ending with the flour mixture.
Line a cupcake tin with liners and fill ⅔ full with batter. Bake at 350°F for 20-25 minutes until inserted tester comes out clean. Cool completely on wire rack.
To make the frosting:
Beat cream cheese and butter together till smooth. Add remaining ingredients and beat until smooth and creamy. Frost cupcakes and garnish with crushed graham crackers and lime wedge.