Melt the butter.
In a bowl, mix the oat flour, sugar, vanilla extract or vanilla sugar, sifted baking powder, and a pinch of salt.
Make a well in the center, crack the egg into it, then add the melted butter and half of the milk.
Gently whisk from the center outward without overmixing. The batter should remain fairly thick.
Let the batter rest for 10 minutes. Gradually add the remaining milk a little at a time until you reach a softer consistency that will spread slightly in the pan.
Note: If the batter is too thick, add a little more milk.
Heat a non-stick frying pan and lightly grease it with butter using a brush or paper towel.
Pour a small ladleful of batter into the pan and cook until the top starts to set and the pancake can be easily flipped. Turn it over and cook until the other side is golden brown. Transfer to a plate and repeat with the remaining batter.
Serve the pancakes warm, generously drizzled with maple syrup, with a couple of knobs of butter and some fresh fruit such as banana, raspberries, or any fruit you like.