Line a baking dish with aluminum foil or use a silicone brownie bite pan. Arrange almonds in a single layer and set aside.
In a heavy saucepan, combine butter, margarine, sugar, salt, and vanilla extract. Cook over medium-high heat, stirring constantly until the butter melts and mixture starts to boil.
Continue boiling and stirring for an additional 5-7 minutes until the mixture reaches about 300°F (hard crack stage). Pour the hot toffee over the almonds in the prepared dish.
Allow the toffee to cool completely, about 2 hours. Spread melted milk chocolate evenly over the cooled toffee, then sprinkle with ground walnuts.
Let the chocolate set at room temperature or in the fridge. Once set, break into pieces or cut into squares. Store in an airtight container.
Notes
This homemade toffee makes a perfect holiday gift or a sweet treat for any occasion.