Preheat oven to 425 degrees Fahrenheit.
Cut butter into 1 Tbsp slices and place evenly in a 9" x 13" pan or in a cast iron skillet.
Place pan in oven until butter is melted. For a little extra flavor, you can wait until it's slightly browned also.
While the butter is melting, prepare your batter. Place eggs in the blender and whirl on high for 1 minute.
With the motor running, gradually pour in milk, then add flour; continue whirling for an additional 30 seconds.
Pour dutch baby batter into the pan with the melted butter.
Bake at 425 for 17-19 minutes until the Dutch Baby is golden brown and fluffy.
Serve and enjoy immediately. Dutch Babies lose some of the fluff quickly.