Prepare the bananas: Melt butter in a pan and peel bananas. Slice bananas in half lengthwise and widthwise. Once butter is melted, add banana slices and top with brown sugar and cinnamon. Cook on medium to low heat, moving around with a spatula to keep them from sticking. Gently flip the bananas and cook for another minute on the other side until bananas are softened and golden brown. Transfer to parchment paper.