Make brownie layer. Preheat the oven to 350°F. Prepare 13 in. x 9 in. pan with vegetable pan spray.
In a large saucepan, melt butter, brown sugar, cocoa powder and salt over medium heat, stirring often until completely liquid and very warm to the touch. Remove the saucepan from the heat.
Quickly add eggs and vanilla and stir until combined.
Add flour and baking powder and stir until batter is very shiny and combined. Mixture will still be very warm.
Add chocolate chips, stirring as the chips melt. Pour into the prepared pan.
Bake for 20-25 minutes, or until a toothpick inserted in the center of the pan comes out clean. Cool completely in the pan.
Make ice cream layer. Remove ice cream from the container and cut into 3/4 in. thick slices. Place slices on top of brownie and use a spatula to help spread into an even layer. Place in the freezer while preparing the whipped cream.
Make whipped cream topping. Prepare Whipped Icing Mix according to package instructions and spread on top of the ice cream layer.
Top with sprinkles and freeze until ready to serve. When ready to serve, remove from the freezer and let stand for 20 minutes at room temperature to soften slightly.