Heat the oven to 350°.
Line a muffin pan with 9 muffin cups.
In a large mixing bowl, whisk the applesauce, coconut sugar, eggs, vanilla and vinegar or lemon juice until blended.
Add the almond flour, cinnamon, baking soda, salt, cardamom and nutmeg. Stir with a spatula until everything is blended. The batter will be thick.
Peel, core and finely dice the apple. Stir into the muffin batter.
Using a 1/4 cup ice cream/cookie scoop or measuring cup, add heaping 1/4-cup scoops to the muffin cups.
Sprinkle each muffin with the walnuts.
Bake for about 22-25 minutes, rotating the pan 180° halfway through baking.
Leaving the muffins in the pan, let them cool completely on a cooling rack, then enjoy!