ingredients

For the cake:

• 1 box vanilla cake mix, (or white/yellow cake mix)
• 1 (3.4 oz) box instant pistachio pudding
• 3 eggs
• 1 cup oil
• 1 cup milk
• green food coloring optional

For the frosting:

• 1 (3.4 oz) box instant pistachio pudding
• ½ cup milk
• 1 (8 oz) tub frozen whipped topping (COOL WHIP), thawed

instructions

To make the cake:

1. Preheat oven to 350F degrees. Spray two pie pans with cooking spray and line with parchment paper.
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2. Combine dry cake mix with dry instant pistachio pudding. Mix those together until combined. Then add in eggs, oil and milk. Stir just until combined. Stir in about 6 to 8 drops of green food coloring until fully incorporated. Pour into prepared baking dish.
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3. Bake for about 25-30 minutes. If you insert a toothpick into it, it should come out clean when done. Allow cake to cool completely before making frosting.

To make frosting:

1. Pour instant pistachio pudding mix into a mixing bowl. Add in ½ cup cold milk. Stir until combined.
2. Stir in the thawed whipped topping.
3. Put in a few drops of green food coloring to really bring out that green color. About 5 drops or so.
4. Spread frosting onto cooled cake.
5. Slice and serve. If you like, sprinkle with some crushed pistachios.

from https://www.thecountrycook.net/pistachio-cake/