Heat oven to 350 degrees F. Grease three 9-inch round cake pans. Line bottoms
with wax paper; grease the paper. Dust pans with flour, tapping out any excess.
In medium bowl, combine flour, baking powder, baking soda, salt and nutmeg;
In large bowl, using an electric mixer set on medium speed, beat butter
until fluffy. Gradually add sugar; beat for 2 minutes. Add eggs 1 at a time,
beating well after each addition. Stir in pineapple with juice.
With the mixer on low speed, beat flour mixture and buttermilk alternately
into egg mixture. Divide and spread batter evenly among prepared pans.
Bake the layers until wooden picks inserted in centers come out clean, about
Transfer the pans to wire racks; cool for 10 minutes.
Run a knife around side of layers. Invert layers onto wire racks; cool completely.
Assembling the cake: Remove wax paper from cake layers. Use a toothpick
to poke several holes in two cake layers; brush with rum. Place one layer on
serving plate, rum side up. Spread with 1/2 cup filling. Place second layer
on top of filling, rum side up. Top with remaining cake layer. Spoon whipped
cream into a pastry bag fitted with a star tip; pipe a ring of whipped cream
on top of the cake. Arrange pecan halves and pineapple chunks on whipped cream.