Line a baking dish with foil and arrange almonds in a single layer. Set aside.

In a heavy saucepan, combine butter, margarine, sugar, salt, and vanilla. Cook over medium-high heat, stirring constantly until the butter melts and the mixture reaches a rolling boil.

Continue boiling and stirring for 5-7 minutes until the mixture turns a caramel color (about 300°F). Quickly pour over the almonds in the prepared dish or scoops in a brownie bite pan.

Allow the toffee to cool completely, about 2 hours.

Spread melted chocolate over the cooled toffee and sprinkle with ground walnuts. Let set before breaking into pieces.