In a medium saucepan over medium heat, combine the sweetened condensed milk, salted butter, brown sugar and corn syrup. Heat while stirring constantly until the mixture reaches 225°F. or until it hits the softball stage.

Remove from heat and then stir in the 3 large marshmallows. Set aside until needed.

Preheat the oven to 350°F. Line a 8x8 pan with parchment paper and set aside.

In a large bowl, whisk together the butter, brown sugar, granulated sugar, eggs and vanilla until combined.

Fold in the flour, cocoa powder, cornstarch and salt until just combined.

Spread 2/3 of the brownie batter onto the bottom of the prepared pan.

Pour and spread the caramel onto the brownie batter in the pan.

Dollop the remaining brownie batter on top of the caramel and then use a toothpick to swirl the brownie batter into the caramel.

Bake at 350°F for 30-35 min or until the brownies are set. Allow the brownies to cool completely before cutting. Cut with a plastic knife and enjoy!

Best stored in the fridge because it will help the caramel stay where it should once the brownies have been cut.