Step 1: Preheat the Oven: Begin by preheating your oven to 350°F (175°C).
Step 2: Melt the Butterscotch Chips: In a microwave-safe bowl, melt the butterscotch chips at 70% power in 30-second intervals until smooth.
Step 3: Combine Wet Ingredients: In a large mixing bowl, combine the melted butter, dark brown sugar, and melted butterscotch. Whisk until blended, then add the egg and vanilla.
Step 4: Mix Dry Ingredients: In a separate bowl, whisk together the flour, baking soda, and salt. Gradually add to the wet mixture, stirring until just combined.
Step 5: Fold in the White Chocolate Chips: Gently fold in the white chocolate chips until evenly distributed.
Step 6: Pour and Bake: Pour the batter into the lined baking pan and bake for about 20-25 minutes until golden.
Step 7: Cool and Serve: Allow to cool for 10 minutes, then transfer to a wire rack, slice, and enjoy!