Whisk milk, egg and vanilla together. Sift flour and Bi-Carb in a separate bowl. Stir in the sugar. Make a well in the centre and add milk mixture. Whisk until combined.
Heat a large non-stick frying pan over medium heat. Add butter to pan. Using 1/4 cup mixture per pancake, cook pancakes until bubbles appear on the surface. Flip over and cook for a further 3 minutes or until cooked through. Repeat with remaining mixture, brushing pan with butter between batches.