Preheat your oven to 325°F (163°C). Prepare a 9x13-inch baking pan by lining it with parchment paper.

In a large mixing bowl, combine the graham cracker crumbs and sugar. Pour in the melted unsalted butter and mix until the crumbs resemble wet sand. Firmly press this mixture into the bottom of the prepared baking pan. Bake for about 10 minutes, or until golden brown.

Using a mixer, beat the softened cream cheese until smooth. Gradually add granulated sugar and vanilla extract, mixing until combined. Incorporate eggs one at a time. Finally, blend in sour cream and heavy cream until smooth.

Pour the cheesecake mixture over the cooled crust, spreading evenly.

In a saucepan, combine brown sugar, unsalted butter, and salt over medium heat. Stir continuously until melted. Remove from heat, add vanilla extract, and drizzle over the cheesecake batter.

Bake the cheesecake for 50-60 minutes. It's done when the edges are set and the center has a slight jiggle.

Let the bars cool in the oven with the door ajar for about 1 hour. Then transfer to the refrigerator and chill for at least 4 hours, or overnight.