Preheat oven to 350°F.
Prepare the crust: add the crackers to a food processor and process until a fine crumb. Add in the melted butter, vanilla, sugar, salt and pulse until fully combined.
Line a 9×9 inch baking pan with parchment paper. Press the cracker crust mixture firmly into the bottom of the pan in an even layer. Press VERY WELL to help the crust hold together well. Bake 10-15 minutes until a nice golden brown and set aside to cool slightly.
Prepare the creamy margarita filling: Add all the ingredients to a medium bowl and whisk well to combine until smooth and creamy. It's important to have room temperature ingredients for the smoothest mixture.
Pour the mixture over the prepared cracker crust. Bake for about 17-20 minutes or until the edges are set and the middle is just set—it may be a bit jiggly still and that is ok.
Allow to cool on a cooling rack for about 30 minutes to an hour before transferring to the refrigerator to chill for at least 2 hours, ideally 4-6 hours to fully set.
Sprinkle with flakey sea salt and fresh lime zest when slicing.