Mix brownies according to package directions. Pour into a lightly greased springform pan and bake according to package directions.

Mint mousse:

1 cup chopped andes mints (better to use the mostly green ones for color)
6 eggs, separated
3/4 cup heavy cream

In microwave, for about 15 sec, melt the mints set up a double boiler on the stove (best to use a metal bowl.) place egg yolks on top of double boiler and whisk using a wire whisk until pale yellow and frothy. add melted mints and mix until combined. The mix will get stiff.
In a separate bowl, using a hand blender, whisk egg whites until stiff. fold the egg whites into the mint and egg yolk mixture a little bit at a time. Next, whip up the heavy cream with a hand-held blender until thick. Fold this a little at a time into the egg and chocolate mix. Top the cooled brownie with the mousse mixture and leave to set in the refrigerator.
Next, heat the cream, milk, or half & half in a pan on the stove. (Non-stick pans work best) Add the chocolate chips and melt and continually stir over a low heat until you have a chocolate sauce. Top the cooled pie with the chocolate sauce. Decorate with andes mints.
Also, if you wish, you can crush more andes mints and when the pie is set and chilled, brush the sides with melted chocolate and press on the crushed mints.