Key Lime Bars in an 8x8 Pan

Key lime bars in an 8×8 pan make 16 small squares: a graham cracker crust topped with a filling of sweetened condensed milk, egg yolks and lime juice. Bake the crust for 10 minutes at 350°F, then the filling for 15 to 18 minutes, and chill for at least 3 hours.

They are key lime pie in bar form, easier to cut, carry and serve to a crowd than a pie.

Why an 8×8 Pan

One 14-ounce can of condensed milk with 3 yolks and 1/2 cup of lime juice fills an 8×8 crust about 3/4 inch deep. At that thickness the filling sets firm enough to cut clean squares while staying creamy. To double the recipe for a 9×13, use 2 cans and bake the filling for 18 to 22 minutes.

Ingredients

Crust

1 1/2 cups graham cracker crumbs
1/4 cup granulated sugar
6 tablespoons unsalted butter, melted

Filling

1 can (14 oz) sweetened condensed milk
3 large egg yolks
1/2 cup key lime juice (or regular lime juice)
1 tablespoon finely grated lime zest

To serve

Whipped cream and thin lime slices or extra zest

Instructions

Prepare the pan. Heat the oven to 350°F. Line the 8×8 pan with parchment, leaving an overhang on two sides.
Bake the crust. Mix the crumbs, sugar and butter, press them firmly into the pan and bake for 10 minutes. Leave the oven on.
Make the filling. Whisk the yolks until smooth, whisk in the condensed milk, then the lime juice and zest. The mixture thickens slightly as the acid reacts with the milk.

Bake the filling. Pour the filling over the warm crust and bake for 15 to 18 minutes, until the edges are set and the centre barely wobbles.
Chill. Cool for 30 minutes at room temperature, then refrigerate for at least 3 hours, or overnight.
Cut. Lift the slab out and cut it into 16 squares with a hot, dry knife, wiping it between cuts. Top each square with whipped cream.

Key Limes or Regular Limes?

Key limes are smaller and more aromatic, with a sharper, more floral juice, so it takes a lot of them to get 1/2 cup. Regular (Persian) limes work well: you need 4 to 5. Bottled key lime juice is a reasonable shortcut. Fresh zest adds back the aroma.

Storage

Keep the bars refrigerated, covered, for up to 4 days. They freeze well without the whipped cream for up to 1 month. Thaw them in the fridge.

Frequently Asked Questions

Why bake the filling? Baking sets the yolks safely and gives a firm, sliceable texture. Many older no-bake versions rely on raw yolks.

Why is my filling runny? It was underbaked or not chilled long enough. The bars firm up considerably in the fridge.

Key Lime Bars in an 8×8 Pan