Pre-heat oven to 350 degrees F. Line 12-tin muffin pan with silicone muffin cups.
Mix the almond flour, baking powder, salt in a large bowl with a whisk. Add sliced blackberries and stir to coat.
In another separate medium bowl, add the eggs, egg white, almond milk, brown sugar, applesauce, vanilla, lemon juice (about 2 Tbsp) and as much zest as you can get from your lemon. Combine well by whisking it all up with a wire whisk.
Add the wet ingredients to the bowl with the dry ingredients. Stir to combine well with a spatula. Don't over-mix but just until the muffin batter is fully combined and no dry spots exist.
Divide muffin batter between 12 muffin tins. Bake at 350 degrees F for 31-32 minutes. Let cool for a few minutes before eating.