Preheat the oven to 350 degrees.
Cook the bacon in a skillet until crispy. Drain the excess fat and use it to grease the doughnut pan. Crumble the bacon. Set aside.
Combine the cream cheese, eggs, flours, baking powder, and erythriol in a blender or food processor. Pour into a mixing bowl.
Stir in the bacon bits.
Combine the stevia and cinnamon in a small bowl until smooth. Drizzle into the batter, and stir once or twice, just until the batter is marbled with cinnamon.
Pour the batter into a doughnut pan, and bake for 15-20 minutes, or until the doughnuts are cooked through.