Espresso Caramel Bars

1. For the crust, position an oven rack in the middle of the oven. Preheat the oven to 350 degrees F. Spray a 7 x 10 3/4-inch nonstick baking pan with cooking spray. Lay a 6 x 18-inch piece of parchment paper in the pan, allowing the excess paper to overhang the long sides. Spray the parchment paper lightly with cooking spray.

2. In the bowl of a food processor, combine the graham crackers and brown sugar. Process until the mixture resembles fine bread crumbs. Add the melted butter and blend until the mixture is combined. Spread the mixture into the bottom of the prepared pan, pressing gently to form an even layer. Bake for 10 to 12 minutes, until the edges of the crust are golden. Cool at room temperature for 10 minutes.

3. For the caramel, while the crust is cooling, in a medium heavy-bottomed saucepan, combine the heavy cream, butter, brown sugar, and water. Stir over medium heat until the mixture is smooth. Bring the mixture to a boil and cook, without stirring, until a candy thermometer registers 240 degrees F, about 5 to 7 minutes. Carefully pour the caramel over the cooled crust. Allow the caramel layer to cool and set at room temperature, about 30 minutes.

4. For the chocolate layer, combine the chocolate chips and heavy cream in a heat-proof bowl and place over a pan of gently simmering water, making sure the bottom of the pan does not touch the water. Stir until the chocolate has melted and the mixture is smooth, about 3 minutes. Whisk in the espresso powder. Pour the chocolate mixture over the caramel layer and smooth with a spatula. Sprinkle the top with sea salt, if using. Refrigerate for at least 1 hour until firm.

5. Using a warm, damp knife, carefully cut around the edges of the dessert to free it from the pan. Using the paper overhang as handles, carefully remove it from the pan. Cut into 1-inch bars and store refrigerated in an airtight container. Allow the refrigerated bars to come to room temperature for at least 1 to 2 hours before serving.