01 - Preheat oven to 350°F. Line an 8x8-inch baking pan with parchment paper, allowing overhang on sides for easy removal.
02 - Combine graham cracker crumbs, sugar, melted butter, and salt in a medium bowl. Mix until mixture resembles wet sand.
03 - Firmly press crust mixture into the bottom of the prepared pan. Bake for 10 minutes, then remove from oven and set aside.
04 - Whisk eggs and sugar in a large bowl until smooth. Add flour, lime juice, lime zest, milk, and salt. Whisk until thoroughly combined.
05 - Pour filling over the pre-baked crust. Bake for 18-20 minutes until center is just set and no longer jiggles.
06 - Cool completely in pan on a wire rack. Refrigerate for at least 1 hour before slicing.
07 - Dust with powdered sugar and extra lime zest before serving, if desired.