Preheat your oven to 350°F. Line a 9x13-inch baking pan with parchment paper or aluminum foil, leaving some overhang for easy removal.

In a medium bowl, stir together the graham cracker crumbs, 6 tablespoons sugar, and melted butter until the mixture feels like wet sand. Press this evenly into the bottom of the prepared pan.

In a separate medium bowl, whisk together the pumpkin puree, heavy cream, 2 eggs, 3/4 cup sugar, 1 teaspoon vanilla, and pumpkin pie spice until smooth. Pour this mixture over the crust and spread it gently to cover.

In another bowl, beat the softened cream cheese with an electric mixer on medium speed until smooth. Add the remaining egg, egg yolk, 1/2 cup sugar, and 1 teaspoon vanilla, and beat until the mixture is well combined and creamy.

Drop spoonfuls of the cheesecake batter over the pumpkin layer. Use a knife to gently swirl the cheesecake into the pumpkin, creating a marbled pattern. Take care not to cut into the graham cracker crust below.

Bake for 37 to 42 minutes, until the center is set and the edges are lightly golden. Let the blondies cool on a wire rack for 30 minutes, then refrigerate for at least 2 hours until fully chilled.

Once chilled, lift the blondies out using the parchment overhang, slice into squares, and serve.