Lay out a large piece of parchment paper. This should be large enough to fit a 10 x 16" rectangle with room around each side.
Mix together oats and cinnamon. Set aside.
In a heavy duty, thick bottomed pot, combine evaporated milk, heavy cream, sugar, brown sugar, salt, and corn syrup.
Cook over medium - low heat, stirring constantly, until butter has melted and sugar has dissolved.
Turn heat to medium. Stirring constantly, bring mixture to a boil.
Turn heat to medium high. Cook until caramel reaches 240F. Turn off heat. Stir in oatmeal cinnamon mix.
Pour caramel on parchment, spreading into a thin rectangle. Cool completely. Make cream filling as it cools.