Hi Jamie, I love a good search and finally found this on the net. Sounds wonderful!

From Southern Living: 1999 Annual Recipies
Pina Colada Cake
Bake: 35 minutes
Chill: 4 hours

1 recipe Basic White Cake Batter(recipe follows)

Pina Colada Filling (recipe follows)

1 recipe Rum Buttercream Frosting (recipe follows)

2 cups flaked coconut

Pour cake batter into 3 greased and floured 8-inch round cakepans.
Bake at 325 degrees for 30 to 35 minutes or until a wooden pick inserted in center comes out clean. Cool in pans on wire racks 10 minutes; remove from pans, and cool on wire racks.
Split layers horizontally. Spread Pina Colada Filling evenly between layers (not on top); cover and chill at least 4 hours.
Spread Rum Buttercream Frosting on top and sides of cake; spinkle top and sides evenly with flaked coconut, pressing in gently.
Store in refrigerator (Freeze up to 1 month, if desired.) Yield: 1 (6-layer) cake.

Basic White Cake Batter

1/2 cup butter, softened
1/2 cup shortening
2 cups sugar
3 cups cake flour
4 teaspoons baking powder
1/2 teaspoon salt
2/3 cup milk
2/3 cup water
2 teaspoons vanilla extract
3/4 teaspoon almond extract
6 egg whites
Beat butter and shortening at medium speed with an electric mixer until creamy; gradually add sugar, beating mixture well.

Combine flour, baking powder, and salt; add to butter mixture alternately with milk and water, beginning and ending with flour mixture. Beat at low speed until blended after each addition. Stir in favorings.

Beat egg whites at high speed with an electric mixer until stiff peaks form; fold about one-third of egg whites into batter. Gradually fold in remaining egg whites. Yield: about 7 cups.

Pina Colada Filling

Cook: 10 minutes
Chill: 4 hours

1 (10 1/2-ounce) can frozen pina colada mix concentrate, thawed and undiluted
1/4 cup cornstarch
6 egg yolks
1 1/2 cups half-and-half
3 tablespoons butter or margarine, cut up
1 cup flaked coconut
1 teaspoon vanilla extract
Bring first 4 ingredients to a boil in a 3-quart saucepan over medium heat, whisking constangly.
Boil, whisking constantly, 1 minute. Remove from heat; whisk in butter and remaining ingredients.
Pour mixture into a bowl. Cover and chill at least 4 hours. Yield: 3 3/4 cups. Rum Buttercream Frosting
1/2 cup butter, softened
1 (16-ounce) package powdered sugar
3 tablespoons rum
3 tablespoons milk
1 teaspoon vanilla extract
Beat butter at medium speed with an electric mixer until creamy; gradually add 1 cup powdered sugar, beating at low speed until blended.
Add rum, milk, and vanilla, beating until blended. Gradually add remaining powdered sugar. Yield: 2 1/2 cups.