Pulse the cookies in a food processor until finely ground. Add the melted butter and pulse until well combined. Quickly pulse in the chopped pecans. Press into a 9-inch pie plate and bake until set, about 10 minutes. Place the pie plate on a rack to cool.
For the chocolate mousse filling: In a microwave-safe bowl, combine the chocolate and butter and melt for 30 seconds. Stir and melt for an additional 20 seconds until the chocolate has thoroughly melted. Whisk in the egg yolks and set aside.
In a chilled bowl with an electric mixer on medium speed, whisk the cream to form soft peaks, about 4 minutes. Add the granulated sugar, espresso powder and vanilla and whisk to form stiff peaks. Fold a third of the whipped cream into the chocolate mixture and mix thoroughly until smooth. Transfer the chocolate to the remaining whipped cream and gently fold in until smooth. Pour the filling into the prepared crust and chill for at least 2 hours before serving.
For the whipped topping: In another chilled bowl with an electric mixer, whisk the cream to form soft peaks. Add the powdered sugar and coffee liqueur and whisk to form stiff peaks.
Top the pie with whipped cream, pecans and toffee pieces and serve. Bake with soul. Eat with pleasure!
Consumption of raw or undercooked eggs, shellfish and meat may increase the risk of foodborne illness.