This creamy dessert is a cross between Key lime pie and traditional lemon bars. For a lighter version, substitute fat-free sweetened condensed milk.
(1/2 stick) unsalted butter, melted and cooled, plus more for pan
(4 ounces) graham-cracker crumbs
grated lime zest
Preheat oven to 350 degrees. Brush an 8-inch square baking dish with melted butter. Line bottom with parchment paper, leaving a 2-inch overhang on two sides.
In a food processor, finely grind pistachios with graham-cracker crumbs, sugar, and zest. Blend in butter. Press mixture into bottom and 1 inch up sides of prepared pan. Bake until lightly browned, 8 to 12 minutes. Cool crust, 30 minutes.
large egg yolks
(14 ounces) sweetened condensed milk
fresh lime juice
To make the filling: In a large bowl, whisk together egg yolks and condensed milk. Add lime juice; whisk until smooth. Pour filling into cooled crust; carefully spread to edges.
Bake until set, about 15 minutes. Cool in pan on rack; then chill at least 1 hour before serving. Using parchment paper overhang, lift out of pan, and transfer to a cutting board. With a serrated knife, cut into 16 squares, wiping knife with a damp kitchen towel between each cut.
Cook's Note: Lining the pan: Cut parchment 8 inches wide and at least 12 inches long. Place parchment in buttered pan (butter will hold paper in place) so it hangs over the sides. This will help you lift the bars out easily.