In a mixing bowl whisk together the melted butter, egg, sugar and vanilla until combined.
Add the mashed banana and buttermilk to the wet mixture and whisk to combine.
In a separate bowl combine the flour, oat flour, baking soda and a pinch of salt, then fold the dry ingredients into the wet until just combined; do not overmix.
Gently fold in the blueberries, being careful not to crush them.
Heat a non-stick frying pan over medium heat and add a little butter to coat the surface.
When the butter is sizzling, pour about 1/4 cup portions of batter into the pan to form small pancakes and cook until bubbles form on the surface, then flip and cook until golden on the other side (about 2–3 minutes per side).
Keep cooked pancakes warm in a low oven while you finish the rest, then serve.