Make brownie mix according to the package directions. Allow to cool completely.
18.3 ounces boxed brownie mix
In a heavy bottomed, medium saucepan, mix the cream, butter, and brown sugar. Cook over medium heat, stirring frequently, until mixture comes to a boil.
½ cup whipping cream, 6 tablespoons butter, 1 ½ cups packed light brown sugar
Once the mixture boils, continue cooking for 1 minute, stirring constantly.
Remove from heat. Stir in pecans, sifted powdered sugar, and vanilla extract.
½ cup chopped pecans, 1 ½ cups powdered sugar, 1 teaspoon vanilla extract
Cool the praline mixture for 5 minutes, stirring frequently.
Spread frosting over brownies.
Allow to stand for 30-45 minutes or until frosting is set. Cut into approximately 1 1/2 inch square pieces.
Notes
To toast pecans, place them in a small baking pan and bake for 5-6 minutes at 350 F. Watch carefully and remove them immediately when they're lightly toasted and fragrant.
Store in an airtight container at room temperature for up to 3 days or freeze individually wrapped pieces for up to 3 months.