Position an oven rack in the bottom third of the oven and preheat the oven to 325 degrees F.
Combine the cream cheese, erythritol, sour cream and egg in a large bowl and beat with a mixer until well combined; set aside.
Generously spray a 9-by-5-inch loaf pan with nonstick coconut spray.
Whisk together the flours, pumpkin spice, baking powder, salt in a medium bowl and set aside.
Whisk together the pumpkin puree and erythritol in a large bowl, then whisk in the melted butter, stevia, vanilla and egg.
Whisk in the flour mixture until just combined.
Reserve 1 cup of the pumpkin batter. Spread the remaining batter in the bottom of the prepared loaf pan.
Spoon the cream cheese mixture over the pumpkin batter, then put the reserved cup of pumpkin batter on top of the cheesecake layer.
Bake until the top is cracked and a cake tester inserted in the center comes out clean, 70-80 minutes. Cool on a wire rack for 20-30 minutes until cheesecake layer is set, then carefully invert onto a platter or cake stand and flip upright.
Let cool completely, at least 1 1/2 hours.
NOTE: Make sure to check on the bread starting at 60 minutes to make sure any cheesecake layer the settled at the top isn't burning. Slightly browned is fine!