Turn key lime pie into fudge with this easy recipe This key lime pie fudge takes the classic flavors of key lime pie and recreates them in fudge form. Creamy white chocolate fudge, flavored with lime zest and fresh lime juice, sits atop a crunchy graham cracker crumb crust. This recipe tastes best if you use good-quality white chocolate, but you can substitute white chocolate chips if that's what you have on hand. Key limes are different from persian limes (the standard grocery store lime). Key limes are smaller and seedier, have a higher acidity, a stronger scent, and a thinner rind than a persian lime. They are picked when they are green but key limes turn yellow when ripe. If possible, use key limes for this recipe. If you cannot find fresh key limes, many grocery stores sell bottled key lime juice. If that's not available, standard (persian) limes will work.