Preheat your oven to 350°F (175°C). In a food processor, pulse the Biscoff cookies until they turn into fine crumbs.

Melt your vegan butter, then combine it with the cookie crumbs, blending until the mixture is clumpy. Press this mixture into an 8x8-inch lined baking dish and bake for 5-8 minutes.

In a mixing bowl, blend together erythritol, cornstarch, and vegan cream cheese until smooth and creamy, about 2-3 minutes. Reserve 1 cup of this mixture in a separate bowl.

Spread the remaining cheesecake mixture evenly on the baked Biscoff crust. In the reserved mixture, mix in pumpkin puree and pumpkin spice, then spread this over the original layer.

In your food processor, pulse together walnuts, brown sugar, gluten-free flour, pumpkin spice, and salt until finely combined. Add melted vegan butter and a splash of water, pulsing until crumbly.

Evenly sprinkle the streusel topping over the pumpkin cheesecake layer. Bake for 25 minutes, or until edges are set and center has a slight jiggle.

Let the bars cool to room temperature on a wire rack. Once cooled, cover and refrigerate for 4-6 hours to solidify.