PREHEAT oven to 350° F. Grease 9-inch (10-cup) tube pan and flour with 3 tablespoons flour.
SIFT remaining 2 1/2 cups flour, baking powder and salt into medium bowl. Beat butter in large mixer bowl until creamy. Add brown sugar gradually and continue beating until light and loose, about 4 to 5 minutes. Beat in eggs, one at a time, beating well after each addition. Gradually beat in flour mixture alternately with 1 cup evaporated milk. Stir in rum until just mixed. Spoon batter into prepared pan.
BAKE for 55 to 60 minutes or until knife inserted in center comes out clean. Cool completely in pan on wire rack. Invert onto plate. Spread Carnation Frosting on top and side of cooled cake. Garnish, if desired, with guava shells. Store in refrigerator.
FOR CARNATION FROSTING
BEAT butter and powdered sugar in large mixer bowl until creamy. Add 1/4 cup evaporated milk and vanilla extract; mix until smooth. Makes 2 cups.
NOTE: A 10-cup Bundt pan can also be used. Follow recipe above and bake for 50 to 55 minutes.