Ingredients:

Cake:
2 1/4 cups self rising flour
2/3 cup vegetable oil
1 1/3 cup sugar
3 eggs, unbeaten
1 tbsp. Grated grapefruit rind
3/4 tsp. Grated lemon rind
1/2 cup grapefruit juice
1/2 cup water

Grapefruit cream filling:
1/2 cup sugar
2 tbsps. Cornstarch
1/4 tsp. Salt
1/2 cup fresh grapefruit juice
1 tbsp. Margarine
1 egg yolk
1 tbsp. Grated grapefruit rind

Directions:

Cake:
Preheat oven to 350 degrees. Cream together oil, sugar and rinds. Beat in eggs one at a time. Sift in flour in three portions, alternating with grapefruit juice and water in two portions. Beat batter 1/2 minute. Pour into 2 well-greased, lightly floured round 9-inch cake pans. Bake 30 minutes or until done. Turn out on a wired rack to cool. When cool, spread grapefruit cream filling between layers.

Grapefruit cream filling:
Combine sugar, cornstarch and salt. Blend in grapefruit juice. Cook over medium heat, stirring constantly, or over hot water until mixture is thick.
Add remaining ingredients. Cook over low heat 5 minutes, stirring constantly.
Cool before spreading.

Frost with your favorite frosting.