Place top rack in the middle of the oven and preheat to 425ºF.
In your blender, add flour, milk, eggs, sugar, melted butter (4 tablespoons) and vanilla extract. Blend for 1 minute, then let batter rest.
Meanwhile, cut 2 tablespoons butter into 12 pieces and add one to each well of your muffin tin. Place in oven for just a minute or until the butter has melted — being extra careful not to let the butter burn!
Remove the muffin tin from the oven and give a quick sprits of non-stick cooking spray to the sides of each well. Give your batter a quick pulse in the blender. Fill each muffin tin well approx. halfway with batter — about 1/3 cup.
Bake until the Dutch babies are puffed and lightly golden brown, 12 to 15 minutes. Let cool for 1 minute before topping and serving!