Arrange almonds in a single layer on a foil-lined baking dish or in a silicone brownie bite pan. Set aside.

Combine butter, margarine, sugar, salt, and vanilla extract in a heavy pan. Cook over medium-high heat, stirring constantly until butter melts and mixture boils.

Continue boiling and stirring for an additional 5-7 minutes until the candy turns the color of almonds, about 300 degrees. Pour over almonds and quickly transfer to each cavity of the brownie bite pan if using.

Let the toffee cool completely, about 2 hours.

Spread melted chocolate over the cooled toffee. Sprinkle with ground walnuts. Allow the chocolate to set before serving or storing.