Preheat the oven to 350 degrees (F).

Line an 8 x 8-inch pan with aluminum foil. Spritz with non-stick cooking spray.

In a large mixing bowl, whisk together the melted butter and brown sugar until well combined.

Whisk in the egg, vanilla and salt.

Using a spatula, fold the flour into the sugar mixture, just until combined. Don't over mix.

Stir in the butterscotch chips, then spread in the prepared pan.

Bake 20 to 23 minutes. The top will look shiny and the edges will start to crack a bit. Don't over bake. 

Allow the brownies to cool completely in the pan, then using the foil, remove from the pan and place on a cutting board.

In a small bowl melt the semi-sweet chocolate chips with 1/2 teaspoon vegetable oil in the microwave. Start with 30 seconds, remove and stir the chips then heat in 15 second increments stirring each time until chips are fully melted.

Drizzle over the cooled brownies.

In a small bowl melt the butterscotch chips with 1/2 teaspoon vegetable oil in the microwave. Start with 30 seconds, remove and stir the chips then heat in 15 second increments stirring each time until chips are fully melted.

Drizzle the butterscotch perpendicular to the chocolate drizzle or channel Jackson Pollock. 

Allow the drizzle to harden then slice into 16 squares. (You can place in the refrigerator to harden the chocolate more quickly.)