Phase 1: Preparing the Buttery Base

1. Preheat and Prepare: Preheat your oven to 180°C (160°C Fan / 350°F / Gas Mark 4). Grease your 20cm x 30cm baking tin and line it thoroughly with parchment paper, leaving an overhang on the longer sides. This overhang will act as handles, making it much easier to lift the slice out once baked.
2. Cream Butter and Sugar: In a large mixing bowl, combine the softened 200g of unsalted butter and 100g of caster sugar. Using an electric mixer on medium speed (or a wooden spoon and vigorous effort), cream them together until the mixture is pale, light, and fluffy. This should take about 3-5 minutes. Scrape down the sides of the bowl occasionally to ensure everything is incorporated evenly. This step incorporates air, which contributes to the tenderness of the base.
3. Add Egg Yolk and Vanilla: Add the 1 large egg yolk and 1 teaspoon of vanilla extract to the creamed butter and sugar. Beat again until just combined. The mixture might look slightly curdled at this stage, which is perfectly normal.
4. Incorporate Flour and Salt: Sift the 300g of plain flour and the pinch of salt directly into the wet ingredients. Using the mixer on its lowest speed, or a spatula/wooden spoon, mix until the flour is just incorporated and a soft dough begins to form. Be very careful not to overmix at this stage; overmixing develops gluten and can result in a tough base rather than a crumbly, shortbread-like texture. The dough will be quite soft.
5. Press Dough into Tin: Transfer the soft dough into your prepared baking tin. Using your floured fingertips or the back of a floured spoon, gently and evenly press the dough into the base of the tin, ensuring it reaches all corners and is relatively level. If the dough is too sticky, lightly flour your hands.
6. Blind Bake the Base (Optional but Recommended): For an extra crisp base, you can lightly dock the dough with a fork (prick it all over) and then blind bake it. Cover the dough with a piece of parchment paper and fill with baking beans or uncooked rice. Bake for 15 minutes. Carefully remove the parchment and beans/rice, then bake for another 5-7 minutes until the base is very lightly golden. If you skip blind baking, simply bake for 10-12 minutes until it’s just set and very pale. This initial bake prevents a soggy bottom.

   • Note: Even a short pre-bake of the base without beans helps to set it before the jam and topping are added.

Phase 2: Assembling the Layers

1. Spread the Jam: Once the base is lightly pre-baked (or if you’ve skipped the full blind bake, after its initial short bake), remove it from the oven. Carefully and evenly spread the 250g of raspberry jam over the warm base, leaving a very small (approx. 0.5cm) border around the edges. This helps prevent the jam from bubbling out too much and burning against the sides of the tin.
2. Prepare the Coconut Topping: In a separate, clean, grease-free mixing bowl, place the 3 large egg whites. Using an electric mixer with clean beaters (or a balloon whisk and strong arm), whisk the egg whites until they form soft peaks. This means when you lift the beaters, the peaks will hold their shape for a moment but then gently curl over.
3. Gradually Add Sugar: Once at the soft peak stage, begin to add the 150g of caster sugar to the egg whites, one tablespoon at a time, whisking continuously until each addition is fully incorporated. Continue whisking until the mixture is thick, glossy, and holds stiff peaks. This is essentially creating a meringue base for your topping.
4. Fold in Coconut and Vanilla: Gently fold the 200g of desiccated coconut and 1/2 teaspoon of vanilla extract into the meringue mixture using a large metal spoon or spatula. Use light, cutting and folding motions to incorporate the coconut without knocking too much air out of the egg whites. The mixture should be thick and well combined.
5. Spread Topping: Carefully spoon the coconut topping mixture over the jam layer. Using the back of a spoon or an offset spatula, gently spread the coconut mixture evenly to cover the jam completely, right to the edges. Try to maintain as much volume as possible.

Phase 3: Baking to Golden Perfection

1. Bake the Slice: Return the assembled slice to the preheated oven (180°C / 160°C Fan / 350°F / Gas Mark 4). Bake for 25-30 minutes, or until the coconut topping is beautifully golden brown and feels firm to a light touch. The exact baking time can vary depending on your oven, so keep an eye on it, especially towards the end. If the topping starts to brown too quickly, you can loosely tent the tin with a piece of aluminium foil.
2. Cool Completely: Once baked, remove the Coconut Jam Slice from the oven and place the tin on a wire rack. Here comes the crucial part: allow the slice to cool completely in the tin before attempting to remove or slice it. This can take at least 2-3 hours at room temperature, or you can speed it up slightly by placing it in the refrigerator once it’s no longer hot. Cooling is essential for clean, neat slices; cutting it while warm will result in a crumbly mess.
3. Slice and Serve: Once fully cooled, use the parchment paper overhangs to carefully lift the entire slice out of the tin and onto a cutting board. Using a large, sharp knife, cut the slice into squares or rectangles of your desired size. Wipe the knife blade clean between cuts if necessary, especially if jam is sticking, to ensure neat edges.