Prepare 16x12x1-inch sheet pan (half sheet) by lightly greasing or spraying with non-stick cooking spray.
Cut open one end of pouch and squeeze batter into prepared pan.
Spread batter with spatula until even.
For convection oven, bake at 325°F 27-32 minutes; for standard oven, bake at 375°F 36-41 minutes.
Allow brownies to cool completely before applying caramel sauce.
In a microwave safe bowl, add butter, cream and sugar.
Microwave on high, 1 min. Remove and stir. Microwave another 30 seconds and stir. Sauce should be golden caramel color. If not, microwave another 30 seconds. *Be careful not to burn the caramel, as it will continue to cook after removing from the microwave.
Add salt and vanilla and stir until uniform in color.
Pour and spread warm caramel over finished brownie.
Use a plastic knife to cut into 3 x 3-inch squares.
Sprinkle flake salt over cut brownies as a pleasant visual.