Line a 9 x 13 baking pan with parchment paper. Set aside.
Add butter, sugar, and salt to a heavy-bottomed saucepan over low to medium-low heat. Mix until fully incorporated and butter is not separated from the sugar.
Continue cooking, stirring frequently until rich golden brown in color and candy thermometer reaches 285℉.
Remove toffee from heat, stir in vanilla extract and ½ cup of chopped almonds.
Quickly pour toffee onto parchment-lined baking pan.
Sprinkle chocolate chips over hot toffee and let sit for 1-2 minutes to soften.
Spread chocolate into an even layer and immediately sprinkle remaining ½ cup of chopped almonds over chocolate. Press almonds lightly into chocolate. Allow to cool completely until hardened.