Spray an 8×8 inch baking dish with cooking spray and set aside.
In a large bowl mix together eggs, milk, brown sugar, melted butter, baking powder, vanilla, cinnamon and salt until combined then stir in rolled oats.
Pour mixture into prepared baking dish and bake for 35-40 minutes.
White Sauce
In a medium saucepan add milk, sugar, vanilla and cornstarch and whisk until cornstarch is dissolved.
Cook over medium, stirring frequently and bring to a low boil then reduce heat and simmer, stirring occasionally until sauce thickens.
Remove from heat and cool.
Once cool pour into a bowl or container with a lid and store in an airtight container.