Add butter, corn syrup, sugar and sea salt to a pot on medium to low heat.
3 tablespoons butter, 1 cup light corn syrup, 1 cup sugar, ½ teaspoon sea salt
Stir syrup mixture until sugar is dissolved, being careful not to let the mixture boil. If you see bubbles remove from heat right away.
Add peanut butter and vanilla to syrup mixture. Stir till combined on low heat.
1 ½ cups peanut butter, 2 teaspoons vanilla
Add cereal to large bowl and pour peanut butter syrup mixture over the cereal.
7 cups rice crispy cereal
Spray a spatula with non-stick cooking spray and gently mix till cereal is coated being careful not to crush cereal.
Spoon cereal mixture into a 9x13 casserole dish that has been well greased or lined with parchment paper.
Gently press cereal mixture, careful not to compress, till bars are flat and even.
In a microwave safe bowl add chocolate and butterscotch chips.
2 cups butterscotch chips, 2 cups chocolate chips
Cook in 20 second invervals stirring chocolate mixture between each round until the topping mixture is just melted. (Do not overheat or it will seize.)
Pour topping over your base mixture and spread evenly. Sprinkle with sea salt if you'd like.
Allow bars to cool before cutting.