Line a 9x9" square pan with aluminum foil, making sure there is extra hanging over the edges. Prepare and bake brownie according to package directions. Remove from oven and let cool to room temperature.

Make the no-churn ice cream: In a mixing bowl, add the sweetened condensed milk, cream, peanut butter and vanilla. Begin whipping the cream mixture on a medium/high speed for approximately 4 1/2 to 5 minutes. Be careful not to over-whip the cream. Cream mixture will begin to thicken. Pour ice cream mixture over cooled brownie. Top with the chopped peanut butter cups. Cover with plastic wrap and freeze for at least 4 hours or over night.

Once ice cream is frozen, prepare the chocolate peanut butter ganache by placing the chocolate chips and peanut butter in a microwave safe bowl. Melt on 30 second increments, stopping to stir. Continue until melted and smooth. Pour over the top of the frozen ice cream, and spread evenly. Top each square with a halved peanut butter cup, if desired. Refreeze ice cream for another 30 minutes before slicing and serving.