Preheat the oven to 350°F.
In a large bowl, beat the softened butter, brown sugar, and granulated sugar together until creamy.
Add the eggs and vanilla and beat until well combined.
In a separate bowl, whisk together the flour, baking soda, and salt.
Add the dry ingredients to the butter mixture and mix until just combined.
Stir in the oats, chocolate chips, butterscotch chips, and chopped nuts.
Drop rounded spoonfuls of dough onto an ungreased baking sheet, leaving about 2 inches between cookies.
Bake for 10–12 minutes, or until the edges are lightly golden and the centers are still slightly soft.
Let the cookies cool on the baking sheet for about 1 minute, then transfer them to a wire rack to cool completely.