Preheat oven to 350 degrees F and line a baking sheet with parchment paper. Set aside.
Add cake mix, vegetable oil and eggs to a bowl and mix well. Dough will be a little stiff, but continue to mix until combined well.
Use a 2 tablespoon portion scoop to scoop dough onto prepared baking sheet. Bake for 12-14 minutes or until bottoms begin to brow. Remove from oven and let cool on baking sheet for 2 minutes before cooling completely on a cooling rack.
When cookies are cooled completely, dip into white chocolate. Line a cooled baking sheet or hard surface with parchment paper and set aside.
Place half a bag of white chocolate chips into a microwave safe container and heat at 50% powder for 30 seconds. Repeat, stirring after each time in the microwave until completely melted, about 1 minute, 30 seconds total.
Dip half of the cookie into the white chocolate and wipe the bottom edge on the side of the bowl. Place onto prepared baking sheet and sprinkle with walnuts. Repeat until all cookies are dipped.