2) Heat a small saucepan over a medium-high heat. Add the butter and cook, stirring occasionally, until it is browned and has a nutty aroma, about 5 minutes. Remove the pan from the heat and whisk in the brown sugar and rum. Pour the butter-sugar mixture into the cake tin. Using a rubber spatula, spread the mixture out so it covers the bottom of the tin.
3) Quarter the pineapple lengthwise, core, and slice it into about twenty 1cm thick slices. Arrange some of the pineapple slices in a slightly overlapping ring around the inside of the cake tin, leaving the centre open. Place 3 of the slices in the centre in a triangle pattern. Press the slices into the butter-sugar mixture.
To make the cake:
1) Place a rack in the middle of the oven and preheat the oven to 180C/Gas 4. Using a sieve over a large bowl, sift together the flour, baking powder, cinnamon, nutmeg and salt. Set aside.
2) In a large bowl with a hand-held electric mixer, combine the butter and sugar and mix at a low speed until just incorporated. Raise the speed to high and mix until light and fluffy, about 10 minutes. (Occasionally turn the mixer off, and scrape the sides of the bowl down with a rubber spatula.)
3) Add the eggs one at time, waiting for each one to be fully incorporated before adding the next.
4) Reduce the speed of the mixer to low. Add the flour mixture in 3 additions alternating with the milk. Raise the speed to medium and mix briefly until a smooth batter is formed. Pour the batter into the pineapple-lined tin.
5) Bake the cake, rotating the tin once during cooking, until golden brown and a toothpick inserted in the centre of the cake comes out clean, about 1.5 hours. Remove the cake from the oven and allow to cool for 5 minutes.
6) Run a knife around the edge of the tin to release the cake. Carefully invert the cake onto a serving plate and remove the greaseproof paper. Allow to cool completely before serving.