5 boxes (10 ounces total) animal crackers
6 tablespoons brown sugar
Pinch of salt
8 tablespoons (1 stick) unsalted butter, melted
4 ounces cream cheese, room temperature
6 limes: zest from 4; juice from all (about 1 cup)
2 cans (14 ounces each) sweetened condensed milk
2 egg yolks
Heat oven to 325 degrees. Line a 9-by-13-inch pan with heavy aluminum foil, leaving extra length on the ends to use as handles; coat with cooking spray.
Crush animal crackers with rolling pin or food processor. Add brown sugar and salt; drizzle butter over crumbs and combine. Press crumbs evenly and firmly into bottom only of pan. Bake until golden, 18-20 minutes. Cool on rack while preparing filling.
With spatula combine cream cheese, zest and pinch of salt until thoroughly blended. Add condensed milk and whisk until incorporated. Whisk in egg yolks. Add lime juice and whisk until slightly thickened. Pour into crust and bake 15-20 minutes or until set and sides begin to pull away from pan.
Cool on rack to room temperature; cover with foil and refrigerate 2 hours. Lift bars from pan and cut into squares.