Line an 11x7-in. pan with foil and grease the foil with 1 tablespoon butter. Arrange almonds evenly in pan; set aside.
In a heavy saucepan, combine the sugar, salt and remaining butter. Bring to a boil, stirring constantly. Cook and stir until mixture is caramel-colored and a candy thermometer reads 300° (hard-crack stage). Remove from the heat; stir in vanilla. Immediately pour over almonds. Cool completely.
Spread melted chocolate over toffee; sprinkle with walnuts. Let stand until set. Break into pieces. Store in an airtight container.
We recommend that you test your candy thermometer before each use by bringing water to a boil; the thermometer should read 212°. Adjust your recipe temperature up or down based on your test.