INGREDIENTS

• Melted butter for the pan

• 6 ounces (170g) graham crackers (about 11 sheets)

• 5 tablespoons unsalted butter (2.5 oz / 71g), melted and cooled

• 2 tablespoons plus ½ cup sugar (4.4 oz / 125g)

• Several pinches of kosher salt

• 1⅔ cups heavy cream (14 oz / 400g)

• 1 tablespoon finely grated grapefruit zest

• ½ cup fresh red grapefruit juice (4 oz / 113g), from about 1 medium grapefruit

• 3 tablespoons fresh lemon juice, from about 1 medium lemon

• 1½ teaspoons vanilla extract

• 8 ounces (227g) cream cheese, chilled

• 1 medium red grapefruit, for serving

1. PREHEAT THE OVEN AND PREPARE THE PAN: Arrange an oven rack in the center position and preheat the oven to 350°F. Line an 8 × 8-inch baking pan, preferably metal, with foil, working the foil carefully into the corners and pressing it firmly against the sides to eliminate air pockets, and smoothing any creases. Brush the bottom of the foil with a thin layer of melted butter. If you’re using a glass pan, note that those tend to have narrower bases and rounder sides, so your bars will be taller and a little less square.

2. MAKE THE CRUST: Place the graham crackers in a resealable bag, press out the air, and seal. Use a rolling pin or heavy-bottomed saucepan to crush the crackers, periodically shaking the bag so the larger pieces settle to one side, until you have very fine, uniform crumbs. (You can also pulse them in a food processor until finely ground, but it’s very doable by hand.) Transfer the crumbs to a medium bowl and add the melted butter, 2 tablespoons of the sugar, and a pinch of salt. Toss with a fork until the mixture is well combined, then rub it between your fingertips until it looks like wet sand.

3. PRESS IN THE CRUST AND BAKE: Transfer the mixture to the prepared pan and use the bottom of a 1-cup dry measure or glass to flatten it into an even, compact layer. Place the pan on a sheet pan and bake until the crust is fragrant, firm to the touch, and dark brown around the edges, 13 to 18 minutes. Remove from the oven and let cool completely.

4. REDUCE THE CREAM: In a large saucepan, combine the cream, remaining ½ cup (3.5 oz /100g) sugar, and a pinch of salt and bring to a boil over medium-high heat, stirring to dissolve the sugar. Reduce the heat to maintain a lively simmer and continue to cook, whisking occasionally, until the mixture is reduced to 1¼ cups, 10 to 15 minutes (pour it into a heatproof liquid measuring cup to check the volume, then return to the saucepan and continue to reduce if it’s not there yet).

   Potential Pitfall: Keep an eye on the cream mixture, as it will boil over quickly and make a mess. Once it boils, take a minute to regulate the heat and find the level where the mixture is simmering vigorously but not boiling. If it does start to boil over, immediately remove the saucepan from the heat and blow on the surface to make it subside.

5. CHILL THE CREAM MIXTURE: Remove the saucepan from the heat and set aside. Fill a large bowl about a quarter of the way with ice water and place the saucepan inside, making sure that the water level hits below the top of the saucepan. Let it sit, whisking occasionally, until the mixture is cold, about 5 minutes.

6. MAKE THE FILLING: Remove the saucepan from the ice water and stir in the grapefruit zest, grapefruit juice, lemon juice, and vanilla, then set aside. Empty the bowl of ice water, dry it, add the cream cheese, and beat with a hand mixer on medium speed until the cream cheese is smooth. Add a couple tablespoons of the cold cream mixture and beat on medium to incorporate, then continue to beat the cream cheese, gradually adding the cream mixture, until you have a smooth mixture. Increase the speed to medium-high and beat until you have a very thick, whipped filling, about 3 minutes.

   Potential Pitfall: If, despite adding the cream mixture slowly and beating constantly, your filling has lumps of cream cheese, use a blender to smooth it out. If you find that your filling isn’t whipping, it might not be cold enough, so refrigerate it until cold.

7. FILL THE CRUST: Scrape the filling into the cooled crust and use a spatula to work it all the way to the sides and into the corners, taking care not to form any air pockets, then smooth the surface. Cover and refrigerate until the filling is set, at least 4 hours.

8. TOP WITH FRESH GRAPEFRUIT AND SERVE: Use a sharp knife to cut away the peel from the whole grapefruit (discard) and slice the grapefruit crosswise into ½-inch-thick rounds. Then, using your fingertips and working one round at a time, gently separate the individual fan-shaped pieces of grapefruit from the membranes (discard the membranes). Remove the pan from the refrigerator, uncover, and use the edge of the foil to lift the bars out of the pan and transfer to a cutting board. Slice the slab into a 3-by-4 grid, forming 12 bars. Dividing evenly, top the bars with the pieces of fresh grapefruit and serve.

Can I . . .

Make them ahead? Yes. The unsliced bars can be covered and refrigerated in thepan for up to 5 days but are best served by the third day to prevent the crust from becoming soggy. To store leftover bars, remove the pieces of fresh grapefruit, transfer the bars to an airtight container, and refrigerate for up to 3 days.

Make it gluten-free? Yes. Use a brand of gluten-free graham-style crackers for the crust.

Use a stand mixer instead of a hand mixer? Yes. To make the filling, beat the cream cheese in a stand mixer fitted with the paddle attachment on medium speed until smooth, then very gradually stream in the cold cream mixture, beating constantly, and proceed with the recipe as written.