• Preheat the oven to 350°F. Prepare a loaf pan with either a spritz of nonstick cooking spray or a coating of butter.

Make the Bread Batter:

• In a large bowl, cream together the softened butter and sugar substitute until the mixture is light and fluffy.
• Whisk in the three eggs until well combined. Stir in the sour cream, cinnamon, vanilla, and salt.
  
• Stir in the almond flour, baking powder, and water. Set aside for a few minutes.

Make the Cinnamon Swirl:

• In a separate small bowl, combine the melted butter, cinnamon, and sugar substitute. Stir well to make sure the sweetener is fully dissolved and everything is fully incorporated.

Assemble and Bake the Bread:

• Pour half of the batter into the loaf pan. Drizzle half of the cinnamon swirl mixture over the batter. Pour in the remaining batter. Pour the remaining cinnamon swirl mixture on top. Run a knife through the batter in a figure 8 a few times to create a marble effect of the cinnamon mixture in the bread batter.
  
• Bake in the preheated oven until the crust is golden and a knife or toothpick inserted in the center comes out clean, about 45-55 minutes.
• Remove from oven and let the bread cool in the pan for 5-10 minutes. Then run a butter knife around the edges of the loaf and invert the pan to remove the loaf. Transfer it to a wire rack to cool completely, at least 30-45 minutes, before slicing.