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 until butter melts, stirring constantly, until mixture comes to a rolling boil.
Continue boiling and stirring for about 5-7 minutes until the mixture reaches approximately 300°F (hard crack stage). Quickly pour over almonds. Use a small scoop if using a pan with individual compartments.
Allow to cool completely for about 2 hours.
Spread melted milk chocolate over the cooled toffee. Sprinkle ground walnuts on top. Chill until chocolate is set. Cut into pieces if not using a pan.
Notes
This homemade toffee makes a perfect gift or sweet treat for any occasion.