Blitz the rolled oats in a blender or food processor for about 30 seconds, until they look like coarse flour with a few flecks left in. Do not use quick oats — they are pre-steamed and turn to paste rather than flour.

Whisk the oat flour, whole wheat flour, ground flaxseed, chia seeds, baking powder, baking soda, salt and cinnamon together in a large bowl.

In a second bowl whisk the buttermilk, eggs, mashed banana, maple syrup and melted butter. Pour into the dry ingredients and stir only until the last dry patch disappears. Lumps are fine and gluten is not your friend here.

Now leave the bowl alone for 10 minutes. This is the step the recipe exists for: oat flour, flax and chia all absorb liquid slowly, and if they are still absorbing while the pancake cooks you get the dense, faintly damp middle that whole-grain pancakes are notorious for. The batter will go from pourable to falling in a thick ribbon. Do not rest it much beyond 20 minutes or the baking soda will have spent itself.

If the rest has taken it too thick — different oats drink differently — loosen with a splash of milk now, after the rest and never before.

Heat a griddle or heavy frying pan over medium-low with a little butter. Ladle on the batter, then drop the blueberries onto each pancake in the pan rather than stirring them into the bowl, where they burst and streak the batter grey.

Cook about 3 minutes on the first side — longer and lower than white pancakes, because these are thicker and will darken outside before the middle sets. Flip when the bubbles coming up stay open instead of closing over, and give the second side 2 minutes.

Keep the finished ones warm in a low oven on a rack rather than a plate, so the bottoms do not steam soft. Treat the first pancake as the calibration pancake; it always is.