Banana bread is such a great way to use up old bananas, which makes my waste averse self happy.
Put peeled bananas in a large microwave-safe bowl; cover the bowl with plastic wrap and cut a couple of slits in the wrap to act as vents (if you use too small of a bowl, your bananas are going to overflow and make your microwave a sticky mess. Don't ask how I know this). Microwave about 5 minutes, until the bananas are soft and have released liquid. Dump the bananas into a mesh strainer set over a medium saucepan and let drain, pressing the bananas down occasionally, for around 15 minutes (you should have ½-¾ cup liquid in the bottom of the saucepan).
Pour the wet ingredients into the dry ingredients you whisked together earlier and fold together gently, just until combined. Pour the batter into the prepared pan(s).
Sprinkle the sugar evenly over the top.
Bake until a toothpick inserted in the center comes out clean or a gentle press of your finger doesn't leave an indent in the top, 55-75 minutes for a single loaf, more like 30-45 for mini loaves, and about 20-30 for muffins.
Continue to cool and serve warm or at room temperature.