I think this cake originated at the Watergate Hotel or something similar. Haha, nothing scandalous. Because it’s green, we love to make it every year for St. Patrick’s Day. But I love the creamy, thick frosting so much that I’ve even had it for a birthday cake once or twice. Plus, I just love nuts. FYI, sometimes the cake might sink in the middle or get a little dark around the edges, but it’s still always delicious.
If you’re making this one gluten free, I did actually make it gluten free for St. Patrick’s Day this year using a gluten free white cake mix. I added 3-4 Tbsp. corn starch since gluten free versions of things often have you add extra corn starch or gluten free flour–plus a few gluten free mixes say to add a few tablespoons of corn starch for high altitude. I don’t think it necessarily needed that much. Maybe next time I’ll just do 2 Tbsp. corn starch. The batter looked a little thicker than the regular, but it baked up to the same level. I had to use a Funfetti cake mix because the store didn’t have a gluten free, but it turned out just fine. I also toasted some pecans instead of raw walnuts, and it was great.
Watergate Cake

Nutty, with amazing green frosting and perfect for St. Patrick’s Day.
Ingredients
Cake
- 3 ½ oz. box instant Pistachio Pudding
- White Cake Mix (or gluten free cake mix + 2-3 Tbsp. corn starch)
- 1 c. Vegetable Oil
- ½ c. Walnuts or pecans, slightly chopped (optionally toasted)
- 1 c. Ginger Ale
- 3 Eggs
Frosting
- 8 oz. container Cool Whip
- 3 ½ oz. box instant Pistachio Pudding
- 1 ¼ c. Milk
Directions
For cake, mix ingredients and pour into a well-greased 9×13 pan. Bake at 350° for 30-40 minutes.
For frosting, mix and whisk all ingredients until smooth. Let it sit for a few minutes to thicken, then spread on cake.