Line a baking sheet with parchment paper and set aside. Gather all ingredients and tools.
In a heavy-bottomed saucepan, combine 1 cup real butter and 1 cup sugar. Stir over medium heat until butter is melted and sugar is dissolved.
Raise heat to medium-high and bring mixture to a boil, stirring constantly. Cook until mixture reaches a deep golden color, about 300°F, approximately 10-15 minutes.
Remove from heat and stir in 1 tsp pure vanilla extract carefully as mixture may bubble up.
Fold in 2 cups roasted sea salt peanuts until evenly coated.
Pour toffee mixture onto prepared baking sheet and spread evenly with a rubber spatula.
Sprinkle 1 bag semi-sweet chocolate chips over warm toffee. Let sit for a minute to soften, then spread melted chocolate evenly.
Allow toffee to cool at room temperature until completely set, about 1-2 hours. Break into pieces to serve.