Buster Bar Dessert

I grew up in a town that had a Dairy Queen on the town square. Time has passed. The Dairy Queen has moved and I live across the nation. But the Dairy Queen Buster Bar lives on through this dessert.

2 cups confectioner's sugar
12 oz. can evaporated milk
2/3 cup chocolate chips
1 cup butter (divided)
1teaspon vanilla
3 cups crushed chocolate wafers
1/2 gallon vanilla ice cream
2 cups salted, dry roasted peanuts -chopped

In a saucepan bring sugar, milk, chocolate chips and a 1/2 cup of butter to a boil. Reduce heat and simmer uncovered for 8 minutes. Remove from heat and stir in the vanilla. Completely cool.
Melt the second 1/2 cup butter and toss with the chocolate wafer crumbs. Press the butter -  wafer mixture onto the bottom of a 13" x 9" x 2" dish forming a crust.
Cut the frozen ice cream into 1 1/2 " slices and arrange the slices over the crust. Sprinkle the ice cream layer with nuts and freeze 30 minutes. Spread chocolate sauce onto the desert, cover and freeze at least 2 hours. Remove from freezer 15 minutes prior to serving.

The original recipe said this could be frozen for up to 2 months. I've never frozen it for any more than two days. It is a make ahead recipe which I like when the busy days of entertaining arrive.