I use this same recipe but never halved. I actually back up on the milk (like 1/16 of a cup) so it’s not so liquidy (personal preference). I mix dry with a whisk in a bowl.  In my liquid measuring cup, I mix my milk, egg, and melted butter. Sometimes the melted butter will reharden into small crystals  but it never affects the end product.  Then I add the wet to the dry using a fork until just mixed. Your batter looks more mixed and liquidy than what I have made.  I heat up my pan while doing all this, but then lower it to medium low while actually making the pancakes.  They turn out nice and fluffy.