Preheat oven to 350 degrees and line a 9x9-inch pan with parchment paper.
First, prepare your crust. Pulse whole pretzels in a food processor/blender until they are a very fine crumb. You need about 1 ½ cups. In a small bowl, mix together the pretzel crumbs, melted butter and granulated sugar until combined. The mixture will be sandy. Firmly press the mixture into the bottom of your pan. Pre-bake the crust for 10 minutes.
While the crust is baking, prepare the filling. Combine the lime zest, lime juice, greek yogurt and sweetened condensed milk and whisk until you have a smooth and creamy mixture. Pour the filling on top of the crust and bake for 10 minutes, turning the pan half way through. The bars will be done when there is a slight jiggle in the center.
Remove the bars from the oven and let cool at room temperature for five minutes, then transfer to the refrigerator to cool completely. Once your bars are cool, prepare the whipped cream. In a small bowl, beat together the heavy whipping cream and powdered sugar until stiff peaks form. Use a rubber spatula to make a smooth layer on top of the pie bars. Decorate with more lime zest if desired. Cut into bars and enjoy!!Remove the bars from the oven and let cool at room temperature for five minutes, then transfer to the refrigerator to cool completely. Once your bars are cool, prepare the whipped cream. In a small bowl, beat together the heavy whipping cream and powdered sugar until stiff peaks form. Use a rubber spatula to make a smooth layer on top of the pie bars. Decorate with more lime zest if desired. Cut into bars and enjoy!!