1. Preheat the oven to 350°F and line a 9×13-inch baking pan with parchment paper or grease it well.

2. Melt the butter and semisweet chocolate chips together until smooth.

3. Stir in the granulated sugar, flour, rolled oats, and salt until a thick mixture forms.

4. Press about two-thirds of the mixture into the prepared pan and reserve the rest for the topping.

5. Bake the bottom layer for 10 minutes until it begins to set.

6. In a saucepan over medium-low heat, combine the butterscotch chips, evaporated milk, peanut butter, and marshmallow creme, stirring until smooth and creamy.

7. Remove the filling from the heat and stir in the vanilla extract.

8. Spread the nougat-style filling evenly over the partially baked crust.

9. Crumble or spoon the remaining oat mixture over the top.

10. Bake for 18 to 22 minutes, until the top is lightly golden and set.

11. Cool completely, then chill before slicing into bars for the cleanest edges.