Phase 1: Prepare the Buttery Biscuit Base

1. Preheat Oven and Prepare Tin: Preheat your oven to 180°C (160°C Fan / 350°F / Gas Mark 4). Grease your 20cm x 20cm square baking tin and line it with parchment paper, leaving an overhang on two opposite sides. This overhang will act as handles, making it much easier to lift the slice out once it’s chilled.
2. Crush the Biscuits: If using a food processor, pulse the digestive biscuits until they resemble fine crumbs. Alternatively, place the biscuits in a sturdy ziplock bag, seal it, and crush them using a rolling pin until fine. You’re aiming for a sandy texture.
3. Combine Base Ingredients: Transfer the biscuit crumbs to a medium-sized mixing bowl. If using, stir in the desiccated coconut. Pour the melted butter over the crumbs and coconut mixture. Mix thoroughly with a spatula or your hands until all the crumbs are evenly moistened and the mixture resembles wet sand.
4. Press into Tin: Tip the buttery crumb mixture into your prepared baking tin. Using the back of a spoon or the base of a clean glass, press the mixture down firmly and evenly to create a compact base. Pay extra attention to the corners and edges to ensure a solid foundation.
5. Blind Bake (Optional but Recommended): For an extra crisp base, you can blind bake it for 8-10 minutes. This step helps prevent a soggy bottom. If you’re short on time, you can skip this, but the texture will be slightly softer. Remove from the oven and set aside while you prepare the filling.

Phase 2: Create the Luscious Condensed Milk Filling

1. Combine Filling Ingredients: In a medium-sized, heavy-bottomed saucepan, combine the sweetened condensed milk, golden syrup, and the 60g of butter (cut into small pieces).
2. Melt and Simmer Gently: Place the saucepan over low to medium heat. Stir continuously with a whisk or wooden spoon as the butter melts. It’s crucial to keep stirring to prevent the mixture from catching on the bottom of the pan and scorching, which can happen quickly with condensed milk due to its high sugar content.
3. Thicken the Mixture: Once the butter has melted and the mixture is smooth, continue to cook, stirring constantly, for about 5-8 minutes. The mixture should thicken slightly and may bubble gently around the edges. It won’t turn into a deep caramel at this stage, but it will become more viscous.
4. Incorporate Vanilla and Flour (if using): Remove the saucepan from the heat. Stir in the vanilla extract. If you’re using the optional flour for a firmer set, sift it directly into the saucepan and whisk vigorously to ensure there are no lumps. The residual heat will cook the flour taste out.
5. Pour Over Base: Carefully pour the warm condensed milk filling evenly over the prepared biscuit base in the baking tin. Use a spatula to spread it out if necessary, ensuring it reaches all corners.

Phase 3: Bake and Cool

1. Bake the Slice: Place the baking tin in the preheated oven. Bake for 15-20 minutes, or until the filling is lightly golden brown around the edges and just set in the centre. It might still have a slight wobble, which is fine as it will continue to firm up as it cools. Be careful not to overbake, as this can make the filling too hard or chewy.
2. Cool Completely: Once baked, remove the tin from the oven and place it on a wire rack. Allow the slice to cool completely in the tin at room temperature. This can take 1-2 hours. It’s very important that it’s fully cool before you add the chocolate topping, otherwise, the chocolate may not set properly or could separate.

Phase 4: Add the Chocolate Almond Topping

1. Toast the Almonds (if not already toasted): While the slice is cooling, you can toast your almonds. Spread the slivered or flaked almonds on a small baking tray and toast them in the oven (you can do this while it’s still warm from baking the slice, or at around 160°C/320°F) for 5-7 minutes, or until lightly golden and fragrant. Keep a close eye on them as nuts can burn quickly. Alternatively, you can toast them in a dry frying pan over medium heat, stirring frequently. Let them cool.
2. Melt the Chocolate: Once the condensed milk slice base is completely cool, prepare the chocolate topping. Place the chopped dark chocolate and the 30g of butter in a heatproof bowl. You can melt this mixture in one of two ways:

   • Microwave Method: Microwave on medium power in 20-30 second intervals, stirring well after each interval, until the chocolate is almost fully melted. Remove and stir until completely smooth. Be careful not to overheat, as chocolate can seize.
   • Double Boiler (Bain-Marie) Method: Set the heatproof bowl over a saucepan of simmering water (ensure the bottom of the bowl doesn’t touch the water). Stir gently and continuously until the chocolate and butter are melted and smooth.

3. Pour and Spread Chocolate: Pour the melted chocolate mixture over the cooled condensed milk layer. Working quickly, use an offset spatula or the back of a spoon to spread the chocolate evenly across the entire surface.
4. Sprinkle with Almonds: Immediately, while the chocolate is still wet, sprinkle the toasted almonds generously and evenly over the top. Gently press them into the chocolate very slightly if needed to help them adhere.

Phase 5: Chill and Slice

1. Chill Thoroughly: Place the baking tin in the refrigerator and chill for at least 2-3 hours, or preferably overnight. This chilling time is crucial for the slice to set firmly, allowing for clean, neat squares when cutting. The chocolate also needs this time to fully harden.
2. Slice and Serve: Once thoroughly chilled, carefully lift the slice out of the tin using the parchment paper overhangs. Place it on a cutting board. For the neatest cuts, use a large, sharp knife. You can dip the knife in hot water and wipe it dry between cuts for extra clean edges. Cut the slice into squares or bars of your desired size. 16 squares (a 4×4 grid) is a common and manageable serving size.