Preheat oven to 350°F.

Using a food processor or mini-chopper, pulse the graham crackers until finely ground.

Using a medium bowl, combine the graham cracker crumbs, brown sugar and melted butter. Stir until fully combined.

Lightly butter or grease a 9” tart pan with removable bottom. Press the crust mixture evenly into the bottom of the pan. (Tip: A flat-bottomed glass helps pack the crust mixture down evenly.)

Bake crust for 15 minutes. Remove from oven and let cool.

Meanwhile, using a medium saucepan, add raspberries and lemon juice; place over medium-low heat. Cover and cook for 12-15 minutes, or until raspberries are very soft.

Using a medium mixing bowl, whisk together the heavy cream, egg, egg yolks and sugar. Transfer this mixture into the saucepan with the raspberry puree.

Place pan over medium-low heat and cook, stirring often, until mixture thickens and coats the back of a wooden spoon, about 5-7 minutes. (Tip: If you have a candy thermometer or instant-read thermometer, cook mixture until it reaches 170°F.)

Remove from heat and add butter several pieces at a time, stirring after each addition until butter has completely melted and is well combined.

Transfer mixture into cooled crust. Place in freezer for at least 2 hours before serving. (Note: Can be frozen overnight.)

{Optional} Garnish with fresh whipped cream and lemon zest before serving.