Preheat the oven to 350°F. Spray a glass 9x13" pan with nonstick spray.

In a large bowl, combine the graham cracker crumbs, melted butter, and brown sugar. Press the graham cracker mixture firmly into the bottom of the prepared pan.

Bake the crust for 10 minutes. Let the crust cool while you make the filling.

In a medium bowl, beat the softened cream cheese with a hand mixer until smooth. Add ¾ cup of sweetened condensed milk, 1 egg yolk, and the vanilla. Beat again until smooth.

In another bowl, beat the pumpkin, pumpkin pie spice, 1 egg yolk and the rest of the sweetened condensed milk.

Pour the cheesecake filling over the top of the crust. Drop the pumpkin filling by the spoonful on top of the cheesecake layer. Use a dinner knife or skewer to swirl the two fillings together.

Bake the cheesecake oven for 25 to 30 minutes or until the edges start to brown. Let it cool to room temperature and then chill the cheesecake in the refrigerator. Once it's cold, slice into bars and serve.