Line an 8" or 9" square baking pan with parchment paper, creating handles with two strips laid out in a cross shape.

In a large bowl, combine the graham cracker crumbs, brown sugar, sea salt, and pumpkin spice. Pour in the melted butter and mix until well coated. Spread the mixture evenly into the bottom of the prepared pan, packing it tightly.

In a chilled bowl, whip the cold heavy whipping cream until stiff peaks form. Set aside in the fridge.

In a separate bowl, beat the cream cheese until smooth. Add granulated sugar, sea salt, vanilla extract, lemon juice, pumpkin puree, and pumpkin spice. Mix until smooth and creamy.

Carefully fold the whipped cream into the pumpkin cheesecake mixture until no streaks remain.

Transfer the cheesecake mixture over the prepared crust, smoothing the top. Refrigerate for at least 8 hours or overnight.

After chilling, freeze the cheesecake for about an hour for clean cuts. Use parchment handles to lift it out, trim edges, and cut into 12 bars.

Whip the cold heavy cream with powdered sugar and vanilla extract until stiff peaks form. Pipe swirls on top of each cheesecake bar and sprinkle with pumpkin spice.