By America’s Test Kitchen
Key limes are smaller, yellower cousins to the bigger, darker green Persian limes you usually see in the grocery store. They’re more tart, with fragrant, floral juice and used to be grown widely in the Florida Keys, where cooks invented key lime pie as a way to use the juice.
To make these key lime bars, you don’t actually need key limes. They can be hard to find and are so small that you’d have to squeeze 20 of them to get 1/3 cup of juice! Regular Persian limes work just fine; but whatever you do, don’t use bottled lime juice in this recipe (fresh juice has much better flavor!). Then there’s toasted coconut. It’s a great addition to baked goods such as cookies, bars or as a topping for ice cream or oatmeal. It can sometimes burn when you toast it in the oven, so we like to use the microwave, where you can keep a close eye on it as it cooks.
Key Lime Bars Makes 16 bars
For the crust: Vegetable oil spray
5 whole graham crackers, broken into pieces (or 3/4 cup store-bought graham cracker crumbs)
1/3 cup (1 2/3 ounces) all-purpose flour
1/4 cup (1 3/4 ounces) sugar
1/8 teaspoon salt 4 tablespoons unsalted butter, melted
For the filling: 1 (14-ounce) can sweetened condensed milk
1/4 cup (2 ounces) cream cheese, softened
1 tablespoon grated lime zest plus 1/2 cup juice (zested and squeezed from 4 limes)
1 large egg yolk
Pinch salt
1/2 cup (1 1/2 ounces) sweetened shredded coconut, toasted, optional
Whipped cream, optional
1. For the crust: Adjust the oven rack to the middle position and heat the oven to 325 degrees. Make an aluminum foil sling for an 8-inch square metal baking pan. Spray foil with vegetable oil spray.
2. Add cracker pieces, flour, sugar and 1/8 teaspoon salt to food processor. Pulse until crackers are broken into small pieces, about five 1-second pulses.
3. Process until crackers are finely ground, about 30 seconds. Add melted butter and pulse until butter is combined with crumbs, about 10 1 second pulses.
4. Remove the lid and processor blade. Use a rubber spatula to scrape the crumb mixture into a foil-lined baking pan.
5. Press crumbs into an even layer covering on the bottom of the baking pan, then use the bottom of a dry measuring cup to press crumbs firmly into the pan until very flat.
6. Place the baking pan in the oven. Bake until the crust begins to brown at the edges, 15 to 20 minutes. Transfer to a cooling rack and let the crust cool for at least 15 minutes. (Do not turn off oven.)
7. For the filling: Meanwhile, in large bowl, whisk condensed milk, softened cream cheese, lime zest and juice, egg yolk and a pinch of salt until well combined and smooth.
8. Pour the filling evenly over cooled crust. Spread the filling into an even layer to the corners of the pan and smooth the top. Transfer to the oven and bake until the filling is set and no longer jiggles when the pan is shaken gently, 15 to 20 minutes.
9. Remove from the oven and let the bars cool in the pan and on the wire rack for 2 hours. Cover the baking pan with plastic wrap and refrigerate until the bars are chilled and firm, at least 2 hours or up to two days.
10. Remove the bars from the refrigerator and remove the plastic. Use foil to lift the bars out of the baking pan and transfer to a cutting board. Cut into squares. Top squares with toasted coconut or whipped cream (if using) and serve.
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