In a large bowl combine the buckwheat flour, baking powder, salt, sugar and cinnamon. In a separate bowl lightly whisk together the milk and egg. Mash up your banana and add it to the milk mix. Now pour the milk/banana mixture into the flour mixture and mix together. Let this batter stand for as long as you can wait, ideally overnight in the fridge covered in cling film.
The next morning your pancake batter will be very thick, almost a paste. Add the frozen blueberries and 60ml of lactose free milk then stir to combine. Leave on a bench to bring up to room temperature.
Heat a non stick fry pan over a medium heat and add about 1/2tsp of butter, if that. Once the butter has melted add some pancake batter to the fry pan. Personally I add around 3 or 4 table spoons for each pancake. But it's a personal choice depending on how big you want them to be.
When the top of the pancake is covered in bubbles gently lift up the edge and check underneath. I don't like mine too dark, but you can leave them on until you are happy with them. once it's ready to flip gently slide your flipper under the pancake and turn it over.
You could also take the showmanship approach and flip it using just the fry pan and your wrist action. I prefer to eat my pancakes off a plate rather than the floor so I use the flipper tool.
Once you've cooked the other side of the pancake slide it off the fry pan and onto a plate, put the plate in the oven to keep the pancake(s) warm until you have cooked all the batter.
Now, here is the most important part. After you cook each pancake take the fry pan off the heat and wipe out any excess butter using some folded up kitchen towel. Being careful not to touch the pan surface with your fingers! Once the pan surface is free of butter, take another small 1/2tbs and start the process again.