Prepare the pan. Preheat the oven to 350°F (175°C). Line the bottom of an 8-inch round cake pan with parchment paper and lightly grease the sides.
Blend the wet ingredients. Add the pumpkin purée, Greek yogurt, eggs, almond butter, maple syrup and vanilla to a blender. Blend until completely smooth and creamy.
Add the seasonings. Add the pumpkin pie spice, cinnamon, baking powder and salt. Blend briefly until evenly combined.
Bake. Pour the batter into the prepared pan and smooth the top. Bake for 35–45 minutes, until the edges are set and the center is just firm, with a slight jiggle but no liquid movement. Avoid overbaking to preserve the creamy texture.
Cool and chill. Let the cake cool in the pan, then refrigerate for at least 1 hour before slicing. Chilling helps it set and gives it a creamy, cheesecake-like consistency.
Serve. Cut into 8 slices. Enjoy chilled, or top with a spoonful of plain Greek yogurt and a light sprinkle of cinnamon.