Step 1

Grease an 8x8 or 9x9 square baking dish.

Step 2

In a large (preferably non-stick) saucepan over medium-low heat melt butter and marshmallows, stirring frequently. Once melted immediately add peanut butter and vanilla, stirring until combined. Remove from heat and stir in the Rice Krispies.

Step 3

Scoop the mixture into the prepared baking dish and gently press into an even layer. If using the chocolate topping proceed below. If not using the chocolate topping, sprinkle the top of the treats with flaky sea salt and allow to cool to room temperature before slicing and serving.

Step 4

In a small saucepan over low heat, combine chocolate chips, peanut butter chips, and peanut butter. Cook, stirring constantly, until completely melted and smooth. Pour over the top of the bars and smooth into an even layer. Sprinkle the top with flaky sea salt. Allow to cool for several hours, until the topping is set.