Pre-heat oven to 350°F.
In a large bowl, mash bananas till almost smooth. Add eggs and vanilla. Mix.
Add syrup, melted butter, and milk. Mix
Next, add oats, baking powder, and cinnamon. Mix well.
The batter will be very liquidy. Carefully, pour the batter into a 9x13 baking pan. Use a spoon or spatula to smooth and make sure oatmeal is evenly spread in the pan.
Place pan in the oven, uncovered, and bake for 35 minutes.
Allow the oatmeal to cool for 10 minutes before serving.