Step 1

For the crust: Place the graham crackers and brown sugar in the bowl of a food processor. Process until finely ground, about 1 minute. With the processor running, slowly pour in the melted butter. Process the crumbs until they are the texture of coarse sand. Transfer to a deep 9-inch pie plate. Using the bottom of a measuring cup, press the crust into the bottom and up the sides of the pan. Press firmly to pack and make an evenly thick crust. Place in the freezer for 20 minutes.

Step 2

For the filling: In the bowl of a stand mixer using a whisk attachment (or using a hand mixer with beater attachments), whisk the heavy cream to stiff peaks. Transfer to another bowl and set aside.

Step 3

In the same stand mixer bowl, place the sweetened condensed milk, cream cheese and lime zest. Using the paddle attachment, beat on medium-high speed until smooth and well mixed, about 2 minutes, scraping down the sides and bottom of the bowl as needed. Turn the mixer to low speed and slowly add the key lime juice. Increase the speed to medium and mix until well combined. Remove from the stand mixer and gently fold in the whipped cream.

Step 4

Transfer the filling to the pie crust and smooth into an even layer. Refrigerate for 12 hours.

Step 5

Serve topped with additional whipped cream and lime zest.