01 -
Preheat the oven to 350°F (177°C). Grease a 9x13-inch baking dish with nonstick spray or a thin layer of oil.
02 -
In a large bowl, beat the cake mix, one box of pistachio pudding mix, crushed pineapple with its juice, eggs, oil, and shredded coconut until smooth and thick, about 2 minutes.
03 -
Spread the batter evenly in the prepared pan. Bake for 30-35 minutes, until the center springs back lightly and a toothpick inserted in the center comes out with moist crumbs.
04 -
Place the pan on a rack and cool completely, at least 1 hour. Do not add the topping while the cake is warm.
05 -
Whisk the second box of pistachio pudding mix with cold milk until thickened, about 2 minutes. Fold in the thawed whipped topping until even and fluffy.
06 -
Spread the pistachio topping over the cooled cake. Cover loosely and refrigerate for at least 2 hours before slicing.
07 -
Sprinkle chopped pistachios over the cake just before serving. Cut into 12 squares and serve chilled.