In a medium sized bowl, combine the graham cracker crumbs, melted butter, and sugar until it resembles a mixture like wet sand. Press the crumbs into a 9" tart pan (see other options below) and bake for 8-10 minutes until golden brown. Cool.
Meanwhile combine the egg yolks, condensed milk, half n half, zest, and lime juice and whisk until combined evenly. Pour the mixture into the cooled graham cracker crust, lower the oven temperature to 350°F and bake for 8-10 mins, until heated through. Cool, and chill in the fridge for at least 2 hours before serving. Garnish and decorate!
Notes
This can be made in mini 4" tart pans or into bars in a square 8x8 inch pan.