Preheat the oven to 350°F and line a 9x9-inch baking pan with parchment paper, leaving overhang on two sides.
In a medium bowl, stir together the almond flour, coconut flour, granulated sweetener and baking powder. Add the melted butter and egg and mix until a soft dough forms.
Press the dough evenly into the bottom of the pan. Bake for 8 minutes, just until the crust looks dry on top, then set aside.
In a large bowl, beat the cream cheese and powdered sweetener until completely smooth. Add the pumpkin puree, eggs, melted butter, pumpkin pie spice and vanilla and beat until creamy.
Pour the filling over the warm crust and spread it evenly to the edges.
Bake for 35 to 40 minutes, until the edges are puffed and set and the center still has a soft wobble. Avoid overbaking, as the slightly underdone center is what makes this cake gooey.
Cool completely in the pan, then chill for 1 hour for clean slices. Dust with powdered sweetener, lift out using the parchment and slice into 16 squares.