Step 1

If using whole graham crackers, place 4 whole graham cracker sheets in a large zip-top bag. Seal the bag and crush with a rolling pin into fine crumbs (about 3/4 cup).

Step 2

Melt 2 tablespoons unsalted butter in a medium skillet over medium heat. Add the graham cracker crumbs and 1 pinch kosher salt, and cook until fragrant and the crumbs are toasted and crunchy, about 2 minutes. Remove the pan from the heat and let cool while you make the lemon mousse.

Step 3

Place 1/2 cup of the cold heavy cream, 1 tablespoon of the powdered sugar, and 1 pinch kosher salt in a medium bowl (or in the bowl of a stand mixer). Beat with an electric hand mixer on medium speed or whisk by hand until soft peaks form, about 1 minute. (If using a stand mixer, beat with the whisk attachment on medium-high speed until soft peaks form, 1 1/2 minutes. Transfer the whipped cream to another bowl.)

Step 4

Finely grate the zest of 1 medium lemon (about 1 1/2 teaspoons), then juice 1/2 of the lemon until you have 1 tablespoon.

Step 5

Place the lemon juice, 1 teaspoon of the zest, 1/2 cup of the lemon curd, the remaining 2 tablespoons powdered sugar, and 1 pinch kosher salt in a large bowl (or now-empty stand mixer bowl). Beat with the electric hand mixer or whisk attachment on a stand mixer on medium speed until well-combined, about 15 seconds.

Step 6

Add the remaining 1 cup cold heavy cream. Beat on medium speed, scraping down the sides and bottom of the bowl about halfway through with a flexible spatula, until soft peaks form, about 2 minutes.

Step 7

Divide the graham cracker crumbs between 4 (6- to 8-ounce) glasses, jars, or ramekins (about 3 tablespoons each). Transfer the mousse into a large zip-top bag and snip off one bottom corner; pipe a scant 1/4 cup into each glass over the crumbs. Dollop 1 tablespoon lemon curd into each glass over the mousse and use the back of a small spoon to spread it into an even layer. Pipe the remaining mousse (about 1/3 cup each) over the lemon curd.

Step 8

Divide the whipped cream into each glass (generous 1/4 cup) over the mousse. Garnish with the remaining 1/2 teaspoon lemon zest. Refrigerate for at least 4 hours or up to overnight.