Ingredients
1 1/4 cups graham cracker crumbs
3 tablespoons packed dark brown sugar
1/4 teaspoon salt
4 tablespoons unsalted butter, melted and cooled slightly
2 ounces cream cheese, room temperature
1 tablespoon finely grated lime zest
1 (14-ounce) can sweetened condensed milk
1 egg yolk
1/2 cup fresh key lime juice
1/4 cup shredded coconut, toasted (for garnish; optional)
OR 16 candied lime slices (see at bottom; optional)
Directions
Preheat oven to 325F. Make a foil sling for an 8-inch square baking dish, letting the ends hang over so you can use them to lift the bars out after they’ve baked. Spray the foil with nonstick cooking spray.
In the bowl of a food processor, combine graham cracker crumbs, brown sugar and salt and process to combine, about ten 1-second pulses. Drizzle the butter over the crumb mixture and pulse until the crumbs are evenly moistened with butter, about ten more 1-second pulses. Place the mixture into the prepared baking pan and use your fingers to press the crumbs evenly to form the crust in the bottom of the pan. Bake until golden brown, about 15 minutes. Remove the pan from the oven and set on a wire rack to cool while you make the filling.
In a medium bowl, use a rubber spatula to stir the cream cheese, lime zest and salt until softened and thoroughly combined. Add the sweetened condensed milk and whisk until fully incorporated. Whisk in the egg yolk. Finally, add the lime juice and whisk gently until it is incorporated. Your filling mixture will thicken slightly.
Pour the filling on top of the crust, spread it into the corners and smooth the surface with a rubber spatula. Tap pan against counter a few times to let any bubbles in the lime-mixture to escape. Bake until the filling is set and the edges begin to pull away slightly from the sides of the pan, about 15 to 20 minutes.
Cool on wire rack to room temperature, 1 to 1 1/2 hours. If using, sprinkle toasted coconut over the bars at this point . Cover the pan with foil and refrigerate until thoroughly chilled, at least 2 hours. Use the foil “handles” to lift the bars out of the pan then cut them into squares before serving. Place a candied lime slice on each bar, if using. Store the bars in the refrigerator.
Directions for candied lime slices:
You will need 2 large limes, a cup of sugar and a couple of cups of water. Slice limes into thin rounds, blanch in a pot of boiling water for 2 minutes and drain. In the same pot, combine 1 cup water and 1 cup sugar. Bring to a simmer and add lime slices. Simmer for 10-15 min, until the white pith of limes looks translucent (may take longer if pith is especially thick or dense). Drain and spread out on a cooling rack to dry for at least 1 hour.