Heat your oven to 160°C Fan/180°C/355°F/Gas Mark 4.
Grease your baking tin, then cut out two strips of greaseproof (parchment) paper which are the width of the tin and long enough to cover the base and both sides whilst allowing for an overhang of about 2 inches on each side. You will hold the overhang later, to lift the cake from the tin.
Sift your flour, baking powder and salt together.
Beat together your softened butter and sugar until pale yellow, light, fluffy and airy.
Add an egg and a dessertspoonful of your flour mixture and beat on a low setting until fully mixed in. Using your spatula, wipe down the sides and base of your bowl to be sure all of the mixture is incorporated, then repeat with the next egg and so on until all 4 have been mixed in. Be sure that each egg is fully mixed in before another is added.
Add the rest of your flour and your desiccated coconut and beat on a low setting until fully mixed, wipe down with your spatula again.
Add your coconut milk and your vanilla extract and beat on low until just mixed in.
Turn up your mixer to medium-high and give it a good short but fast beat for about 10 seconds.
Pour into your prepared baking in.
Heat your jam in a microwavable bowl for out 10 seconds, to loosen it up a bit.
Place blobs of jam over the top of the cake batter, then take your skewer and spread and swirl it into the cake batter,
Bake in the centre of your oven for 30-35 minutes, or until a skewer inserted into the centre comes out clean.
Remove from your oven and, leaving the cake in the tin, place it on a cooling rack for 5 minutes.
Whilst your cake is baking, toast your desiccated coconut. Place your frying pan onto a high heat and add your coconut. Immediately toss it around with your wooden spoon until half of the coconut beings to brown very lightly, then tip it straight out into a dish to cool.
Again, heat your jam for 10 seconds and then spread it over your cake.
Sprinkle over your toasted coconut.
Leave your cake to continue to cool in the tin for about 20 minutes then, holding opposite sides of the greaseproof paper, lift it from the tin and leave it to continue to cool on your cooling rack. Only remove the greaseproof paper once the cake has fully cooled.
Cut into 16 squares.