• Preheat oven to 350 degrees F.

For the graham crumbles

• In a medium bowl, stir together the graham cracker crumbs and brown sugar. Pour the melted butter over the mixture and stir until well combined.
• Pour into a 9- x 13-inch baking pan. Spread evenly without packing the crumbs. Bake for 15 minutes, stirring halfway through baking time. Set aside to cool.

For the Sweetened Whipped Cream:

• In a large mixing bowl, whip the cream, white sugar, and 1 teaspoon vanilla extract until cream has soft peaks. Transfer half of the sweetened whipped cream to an airtight container and place it in the refrigerator. Reserve the remaining half to use in the filling.

For the Filling:

• In a medium bowl, whisk together the sweetened condensed milk, lime juice, and 1 teaspoon vanilla extract until smooth. Stir in the lime zest.
• Fold in the remaining half of the whipped cream. Transfer mixture to an airtight container and place in refrigerator. Chill thoroughly until thickened, at least two hours or overnight.

To Assemble

• Put approximately 2 tablespoons crumble mixture in the bottom of each of the serving containers. Add a layer of key lime filling and then a layer of whipped cream. Repeat the layers of crumble, filling, and whipped cream. Garnish with a light sprinkle of crumb mixture or lime zest. May be stored, covered, in the refrigerator for 2-3 hours prior to serving.