Pre-heat the oven to 180ºC. Cut 4 of the pineapple rings in half and place evenly around the edges of the cake tin.
Place the remaining 5 pineapple rings onto the bottom of the cake tin. Place a halved glace cherry into the hole of each pineapple ring, and dot the others into any gaps. Set aside.
Place all of the remaining ingredients (except the caster sugar) into a mixing bowl and mix thoroughly with an electric hand whisk, until light and fluffy.
Pour over the pineapple in the cake tin.
Bake the cake for 25-30 minutes until the top is golden brown. If you pop a skewer into the centre, it should come out clean.
Once cooked, leave to stand in the tin for 2 minutes, then turn out onto a plate.
Sprinkle the caster sugar over the pineapple rings on the top of the cake. Using a blow torch, melt the sugar until it is golden and bubbling. You could also use a hot grill to melt the sugar - be sure to turn the cake out onto a suitable tray or dish to do this.
Cut into 8 pieces and serve with custard, or your choice of accompaniment.
You can even serve this cold!