Crush cookies to fine crumbs with a rolling pin. I use my food processor instead. Add melted butter. Mix well. Grease the bottom and sides of a springform pan. Press the crumb mixture on the bottom and partway up the sides of the pan. Try to get an even press (Option B is to press your crust into the bottoms and sides of a 9" pie plate). Chill in freezer. - See note below.
Melt chocolate over a double boiler. If you do not have a double boiler, place a glass bowl with the chocolate on top of a pan, filling the bottom pan partway with water. Once melted, stir in 1 Tbsp butter and sugar. Add evaporated milk slowly. Cook for 2 minutes over hot water, stirring. Remove from heat to cool and thicken. Stir occasionally.
Allow ice cream to melt slightly so it is easier to remove from the container and place on top of the Oreo cookie crust, spreading evenly. I like to mound it slightly in the center. Place back in the freezer.
Once the chocolate mixture is cooled completely, spread it on top of the ice cream and place it in the freezer for a couple of hours or until ready to serve.
Serve with a dollop of whipping cream and optional toppings (chopped nuts, caramel, and chocolate).
Note: If using a pie pan instead of a springform pan, use 22 Oreos and 1/3 cup butter instead
Note: While we love doing this with coffee ice cream, it works with any flavor, so have fun picking out your perfect combination.