Preheat oven to 350°F/180°C and line two baking trays with parchment paper. Set aside.
Melt the butter over low heat. Then, in a large bowl, whisk in the slightly cooled melted butter, brown sugar, and white sugar for one minute until combined.
1/2 cup butter, 1/2 cup dark brown sugar, 1/4 cup white sugar
Add in egg and vanilla and continue whisking.
1 egg, 1 tbsp vanilla
Fold in the flour, rolled oats, baking soda, and salt using a spatula until just combined.
1 cup all-purpose flour, 1 cup rolled oats, 1/2 tsp baking soda, 1/2 tsp salt
Mix in the butterscotch chips and white chocolate chips.
1/2 cup butterscotch chips, 1/2 cup white chocolate chips
Scoop 6 cookie dough balls on each tray at a time. Bake for 12-15 minutes or until the edges are a light golden brown.
Top off with additional butterscotch and white chocolate chips if desired. Cool the cookies on a cooling rack and enjoy!