Butter an 8x8-inch microwave safe baking dish, and set aside.
In a medium bowl, combine the ground graham crackers, melted butter, and 1/2 of the clementine zest. Mix until thoroughly combined.
Press the mixture onto the bottom of the prepared baking dish and set aside.
In your mixer's bowl, beat together the clementine juice, sweetened condensed milk, lemon juice, and vanilla.
Pour on top of the crust and microwave for 10 to 12 minutes, or until set, on MEDIUM-HIGH (about 70%).
Cool completely before serving.
Garnish with powdered sugar and the remaining zest.
Cut into squares and serve.