Four-Layer Pineapple-Ginger Cake

1 pkg. (18.25 oz.) spice layer cake
1 can (8 oz.) crushed pineapple
1 cup water
3 eggs
1/3 cup vegetable oil
1 container ( 8 oz.) frozen non-dairy whipped topping
3 Tbsp. chopped crystallized ginger
Additional slivered crystallized ginger (optional)

Preheat oven to 350 degrees. Spray two 8- or 9-in. square or round cake pans with vegetable cooking spray. Drain pineapple, reserving juice. Beat cake mix with reserved juice, water, eggs, and oil until blended. Pour batter evenly into pans. Bake 22-25 min. or until toothpick inserted in center comes out clean. Cool 10 min.; invert onto cooling racks. Cool completely, then split each layer horizontally into two layers. Reserve I cup whipped topping and 1/3 cup pineapple for cake top. Combine remaining pineapple and whipped topping with chopped ginger. Place one cake layer on serving plate. Spread 1/3 of the pineapple mixture evenly over cake. Top with cake layer and 1/3 of pineapple mixture. Repeat layering, ending with the fourth cake layer. Decorate top layer with reserved whipped topping and pineapple. Garnish with crystallized ginger slivers, if desired. Cover; chill at least I hour before serving. Serves 9.