Preheat oven to 350 degrees. Grease a 9-inch square baking pan.
In a large bowl, combine flour, cocoa, and salt.
Melt butter in a large saucepan and remove from heat. Stir in sugar and vanilla. Quickly whisk in eggs, one at a time.
Add butter mixture to flour mixture and stir until well blended. Spread brownie batter into prepared pan and bake for 25-30 minutes. Cool completely.
Meanwhile, make the mousse by heating marshmallows, DelightFulls Mint Filled Baking Morsels and milk in a medium saucepan over medium-low heat, stirring often until completely smooth. Cool completely.
With an electric mixer, beat whipping cream until stiff peaks form. Stir in cooled chocolate mixture.
Spread mousse evenly over cooled brownies. Refrigerate until set.
To prepare ganache, place 6 ounces Nestlé Toll House Semi-Sweet Chocolate Morsels in a medium bowl.
Heat 1/2 cup cream in medium saucepan until just simmering. Pour over chocolate chips and let stand for a few minutes. Whisk until smooth and shiny.
Let ganache stand until it is cool but still spreadable.
Coarsely chop 1/2 cup of the Nestlé Toll House DelightFulls Mint Filled Baking Morsels. Spread the cooled ganache carefully over the mint mousse layer.
Sprinkle both the whole and the chopped mint morsels evenly over the ganache, pressing into the ganache slightly.
Refrigerate brownies for at least 30 minutes, or until ready to serve. Keep leftover brownies in the refrigerator.