Preheat oven to 180�C. Grease, line and grease again a 20cm x 8cm x 7.5cm (8in x 3.5in x 3in) loaf tin. Cream butter and sugar. Add essence and eggs, one at a time; beat well after each addition. Add ground almonds and mix.
Fold in flour gradually, then stir in rum and milk and blend. Turn out batter into the prepared loaf tin. Sprinkle almond flakes over batter and bake in a preheated oven at 180�C for 10 minutes.
Reduce temperature to 170�C and continue to bake for 35 to 40 minutes or until cake is cooked when tested with a wooden skewer.
Cool cake in the tin for 5 to 10 minutes. Turn out onto a wire rack to cool completely.