03Peel bananas and slice in half length-wise. Set aside.
04Heat a 10-inch top-diameter cast-iron skillet (or similar sized oven-proof skillet) over medium-high heat on the stovetop for 5-10 minutes. Add the remaining 2 Tbsp of butter and stir to melt. Once butter is foaming, add the brown sugar and stir to combine. Add the halved bananas, round side down. Swirl in pan, then flip the bananas so the flat side of the bananas is down. Quickly re-blend or re-whisk your resting batter, then pour the batter all at once into the hot skillet. Immediately transfer the skillet to the preheated oven and bake for 18-22 minutes, or until puffy and golden. *Don't open the oven door while the Dutch baby is baking. You can monitor it's progress with the oven light on and through the glass.
05Remove from oven. Pancake will deflate as it cools. Dust with icing sugar, if desired. Top with ice cream and serve warm from the skillet. *Remember the cast-iron handle is hot. Wrap with a tea towel to avoid someone accidentally grabbing it.