Bring sugar, butter, and evaporated milk to a rolling boil over medium heat. Stir frequently.
Remove from heat and add oats, dry pudding, pumpkin pie spice, and salt. Stir.
Let sit for a few minutes until it cools a little bit. While it's cooling line a cookie sheet with wax paper.
Add white chocolate chips and walnuts to cookie mixture. Gently stir being careful to not over stir or else the chocolate chips will be totally incorporated.
Drop by cookie scoopfuls onto wax paper.
Let sit for at least 15 minutes.
Store in an airtight container.