Preheat the oven to 375ºF. Coat a 2 quart baking dish with cooking spray or butter. You could also use an 8x8 baking dish, an 8 inch cast iron skillet, or 4 individual ramekins.
In a large bowl combine bananas, 1 ½ tablespoons brown sugar, and vanilla. Pour the mixture into the prepared baking dish. Sprinkle with chocolate chunks.
In the same empty bowl, whisk together oats, brown sugar, flour, and cinnamon. Use your fingers to incorporate the softened butter until it is crumbly and evenly distributed. Sprinkle the mixture over the bananas and chocolate. Bake 20-25 minutes or until the crisp is golden and the fruit is bubbly.
Serve warm with a scoop of good quality vanilla ice cream.