Preheat oven to 200C.
Mix flaxseeds with 3 tablespoons of water and let stand for 10 minutes.
In a larger bowl combine flour, cocoa powder, baking soda and baking powder. Add wet ingredients except aquafaba into a different (smaller) bowl. When flaxseeds are ready, add the too and give it a good mix.
Combine mix and dry ingredients. In a clean bowl beat auqafaba with an electric whisk untilstiff peaks form. Fold into the batter.
For the filling simply blend together chestnuts, walnutbutter, almondmilk and vanilla until smooth.
Pour about 3/4 of a tablespoon into each of the 12 preapared muffinforms. Divide filling evenly between them, making sure it is placed in the middle of each muffin. Cover the fillings evenly with the rest of the batter. Top with crushed walnuts.
Decrease temperature to 180C. Bake muffins on the middle rack for about 20 minutes. Let cool completely and Enjoy!