Put the Biscoff cookies in a food processor and pulse until they become crumbs. Mix with melted butter and spread and press evenly in an 8x8 baking dish. Bake at 350 for 10 minutes. (if you don't have Biscoff cookies, use 1 cup graham cracker crumbs mixed with 1/2 cup sugar)

In a bowl add eggs, sugar, margarita mix (save about a spoonful of the margarita mix for the glaze in step 4), 1 Tbsp of lime juice (save the other 1/2 Tbsp for the glaze), flour, and a pinch of kosher salt. Whisk or blend with a hand mixer for 1 minute.

Pour this mixture over the crust and bake at 350 for 30 minutes.

Let cool. Sprinkle some of the powdered sugar over top. With the remaining powdered sugar, mix with the leftover margarita mix and lime juice. Drizzle over top of the margarita bars. Sprinkle with more kosher salt if desired. Put in the fridge for at least an hour before serving.