For the crust:
For the ganache:
For the filling and garnish:
To make the crust, preheat the oven to 350˚ F. In a small bowl, combine the chocolate cookie crumbs, melted butter and sugar. Toss with a fork until well combined and all the crumbs are moistened. Press the mixture into a 9-inch pie pan. Bake for 5 minutes. Transfer to a wire cooling rack and let cool while you make the ganache.
To make the ganache, transfer the chopped chocolate to a small heatproof bowl. In a small saucepan set over medium heat, bring the cream to a simmer. Pour the hot cream over the chocolate and let stand 1 minute. Whisk the mixture in small circular motions until the ganache forms. Whisk in the butter 1 tablespoon at a time until completely incorporated.
Spread a thin layer of ganache over the bottom of the pie crust, just enough to cover it completely (about 1/3 cup). Sprinkle half of the toffee bits over the ganache. Transfer the pie plate to the freezer and chill for about 30-60 minutes, until the ganache is set. Leave the remaining ganache at room temperature, whisking occasionally.
Stir the ice cream with a spoon or spatula to be sure it is evenly softened and spreadable. Mound the ice cream into the pie shell and use an offset spatula to smooth the top. Return to the freezer and chill until the ice cream is set, at least two hours.
If the ganache has firmed up while the pie was chilling, soften it again by heating in a double boiler or microwaving in 20-second intervals, just until it is spreadable but not hot. Using a spatula, spread a thin layer of ganache over the ice cream. Sprinkle the remaining toffee bits on top. (Work efficiently, as the ganache will harden quickly after making contact with the ice cream.) Return to the freezer and chill at least 1-2 hours. Reserve any remaining ganache and let cool until thickened. Transfer to a pastry bag and pipe on decorative swirls, if desired. Chill until set.
Let the pie stand at room temperature for several minutes before slicing. Use a warm, dry knife to slice and serve.