Preheat your oven to 350°F. Line an 8 x 4 inch loaf pan with parchment paper. In a small bowl, whisk together cinnamon swirl ingredients. Set aside.
In a large bowl add the butter, eggs, sour cream/yogurt, vanilla extract. Whisk until smooth.
Add in almond flour, baking powder, erythritol. Whisk until evenly combined and batter is smooth. The batter should be thick.
Add ⅓ of the batter into the prepared loaf pan. Use a spatula to spread the batter evenly across the bottom of the loaf pan. Sprinkle half of the cinnamon swirl mixture over the layer of cake batter in the pan, evenly spreading it across. Add in half of the remaining cake batter. Sprinkle the remaining cinnamon swirl mixture over this layer. Add the remaining cake batter into the pan. Smooth and spread out evenly with a spatula.
Place cake into oven and bake for about 45-50 minutes or until toothpick inserted comes out clean.
While cake is baking, make the icing. Combine cream cheese, butter and powdered erythritol. Beat with a hand mixer until a thick frosting forms. Add milk, 1 tbsp at a time, and whisk into the frosting until it thins out and becomes a pourable icing. After cake has cooled, pour or drizzle icing over the top.
