1. 1. Prepare Your Baking Pan: Preheat your oven to 350 F (175 C). Lightly grease and flour a 9×5-inch loaf pan, or line it with parchment paper, leaving an overhang on the sides to easily lift the loaf out later.

2. 2. Combine Dry Ingredients: In a large mixing bowl, whisk together the almond flour, protein powder, granulated erythritol (or sugar substitute), baking powder, and salt. Make sure there are no lumps and the ingredients are evenly distributed.

3. 3. Mix Wet Ingredients: In a separate medium bowl, whisk together the lemon zest, fresh lemon juice, almond milk, applesauce (or Greek yogurt), eggs, melted coconut oil (or butter), and vanilla extract until well combined and smooth.

4. 4. Combine Wet and Dry: Pour the wet ingredient mixture into the dry ingredient mixture. Stir gently with a spatula or wooden spoon until just combined. Be careful not to overmix; a few small lumps are fine. Overmixing can lead to a tougher loaf.

5. 5. Fill the Pan and Bake: Pour the batter evenly into the prepared loaf pan. Place the pan in the preheated oven and bake for 35-40 minutes, or until a wooden skewer or toothpick inserted into the center of the loaf comes out clean. The top should be golden brown.

6. 6. Cool Before Glazing: Once baked, remove the loaf from the oven and let it cool in the pan for about 10-15 minutes. This helps the loaf firm up before you attempt to remove it. Then, carefully lift the loaf out of the pan using the parchment paper overhang (if used) and transfer it to a wire rack to cool completely.

7. 7. Prepare and Apply Glaze (Optional): While the loaf cools, whisk together the optional powdered erythritol (or powdered sugar substitute) and optional 1-2 tablespoons of fresh lemon juice in a small bowl until you have a smooth, pourable glaze. If it’s too thick, add a few more drops of lemon juice; if too thin, add a little more powdered sweetener. Once the loaf is completely cool, drizzle the glaze evenly over the top.