Preheat oven to 350℉ and line an 8x8 baking pan with parchment paper. If the parchment isn't staying, spray the pan with nonstick cooking spray before placing on the parchment paper.
In a medium saucepan, melt butter over medium heat.
Add milk powder continue cooking, whisking constantly, until golden brown.
Add granulated sugar and whisk until smooth. Take the mixture off the heat and set aside.
In a large bowl, mash bananas until no large chunks remain.
Add egg and vanilla extract. Whisk until smooth.
Add butter and sugar mixture. Whisk until smooth.
Fold in flour, baking soda, cinnamon and salt until just combined. There should not be any streaks of the flour mixture left.
Pour into prepared pan and spread smooth.
Bake at 350 for 15-20 minutes, or until a toothpick inserted in the center comes out clean. Let cool.