Key limes are NOT the same as the limes you see in the supermarket. Key limes are smaller and have more seeds, a thinner skin, and a tarter taste. They get their name from the Florida Keys, where they were first grown.
Key Lime Cups
Serves 41 1/2 graham crackers, broken into pieces
1 tablespoon unsalted butter
1/4 cup (2 ounces) cream cheese
1 (14-ounce) can sweetened condensed milk
1 teaspoon grated lime zest plus 1/3 cup juice, zested and squeezed from 3 limes
2 tablespoons water
1 large egg yolk
Pinch salt
Whipped cream, optional
1. HEAT: Adjust oven rack to middle position and heat oven to 300 degrees.
2. SMASH: Add graham cracker pieces to a large zipper-lock plastic bag. Seal bag, making sure to press out all air. Use a rolling pin to gently pound bag to break crackers into crumbs.
3. MIX: Add graham cracker crumbs and butter to a small bowl. Heat in microwave until toasted, about 1 minute. Stir with rubber spatula to combine.
4. SOFTEN: In a large bowl, microwave cream cheese for 10 to 15 seconds. Whisk softened cream cheese until very smooth.
5. WHISK: Add condensed milk, lime zest and juice, water, egg yolk, and salt to bowl with cream cheese. Whisk until well combined and smooth.
6. FILL: Divide filling evenly among ramekins. Place ramekins on a baking sheet.
7. BAKE AND COOL: Bake until filling is set and no longer jiggles when the baking sheet is gently shaken, about 6 minutes. Let key lime cups cool on a cooling rack for 45 minutes.
8. CHILL: Cover ramekins with plastic wrap and refrigerate until filling is chilled and firm, at least 1 hour or up to 2 days. To serve, dollop with whipped cream, if using, and sprinkle with graham cracker topping.
