These raspberry Mars bars layer buttery shortbread, a chewy caramel-and-chocolate filling, tart raspberry jam and a smooth chocolate topping. The familiar candy-bar flavour makes them rich and sweet, while the raspberry cuts through it; chill the layers between steps for neat slices.
Ingredients
- 125 g (9 tbsp) unsalted butter, softened, plus extra for the pan
- 50 g (¼ cup) granulated sugar
- 175 g (1¼ cups) plain (all-purpose) flour
- ¼ tsp fine salt
- 150 g (about 5 oz) Mars bars, roughly chopped
- 30 g (2 tbsp) unsalted butter
- 120 g (about ⅓ cup) thick caramel or dulce de leche
- 100 g (about ⅓ cup) raspberry jam, preferably seedless
- 150 g (5¼ oz) milk chocolate, chopped
- 1 tsp neutral oil, such as vegetable or sunflower oil
Instructions
- Prepare the pan and oven. Heat the oven to 180°C (160°C fan) / 350°F. Line a 20 cm (8-inch) square baking pan with baking parchment, leaving enough overhang to lift the bars out later. Lightly butter the pan first so the parchment stays in place.
- Make the shortbread base. Beat the 125 g softened butter and sugar in a bowl until creamy. Add the flour and salt, then mix just until the mixture looks like damp crumbs and holds together when pressed. Tip it into the prepared pan and press it into an even layer, paying attention to the corners. Prick the surface several times with a fork.
- Bake and cool the base. Bake for 20–25 minutes, until the shortbread is set and lightly golden at the edges. Transfer the pan to a rack and let the base cool completely before adding the filling. A warm base can make the caramel slide and the jam sink in.
- Prepare the Mars filling. Put the chopped Mars bars, 30 g butter and caramel in a small saucepan. Heat over low heat, stirring frequently, until melted and mostly smooth, about 4–6 minutes. The nougat may leave small soft pieces; that is fine. Do not let the mixture boil, as high heat can make it oily or scorch the sugar. Take it off the heat and let it stand for 5 minutes to thicken slightly.
- Add the filling and jam. Spread the Mars mixture over the cooled shortbread in an even layer. Stir the jam briefly to loosen it, then spoon it over the filling in small dollops. Gently spread the jam into a thin layer with the back of a spoon or a small offset spatula, without mixing it deeply into the caramel. Refrigerate for 20–30 minutes, until the top feels set.
- Top with chocolate. Melt the chopped milk chocolate with the oil in a heatproof bowl set over a pan of barely simmering water, making sure the bowl does not touch the water. Stir until smooth, then remove the bowl and let the chocolate cool for a minute or two. Spread it over the chilled layers. For a crisp top that is easier to cut, avoid making the chocolate layer much thicker than the quantity given.
- Chill and slice. Refrigerate the pan for 1–2 hours, until the chocolate is firm and the filling holds its shape. Lift the slab out using the parchment. Leave it at room temperature for 5–10 minutes, then cut into 16 squares with a large sharp knife. Wipe the blade between cuts; if the chocolate cracks, warm the knife under hot water, dry it thoroughly and cut with a gentle sawing motion.
Tips
- Press the base evenly. An even shortbread layer bakes consistently. Use the flat bottom of a measuring cup to compact it without making it excessively dense.
- Keep the filling gentle. Low heat and frequent stirring help the Mars bars melt without scorching. If it seems too thick to spread, stir in 1 teaspoon of warm water; add no more unless needed.
- Choose thick jam. Runny preserves can seep into the filling and make the bars difficult to slice. If your jam is loose, simmer it briefly in a small pan until it thickens, then cool it completely before using.
- Make clean cuts. Let the slab soften briefly before slicing, but do not leave it out so long that the caramel becomes runny. A warm, dry knife is more effective than pressing down hard on the chocolate.
Serving Suggestions
Serve the bars slightly cool or at room temperature, when the chocolate is crisp and the caramel is chewy. They are rich, so small squares work well with coffee, black tea or a glass of cold milk. For a plated dessert, add fresh raspberries and a spoonful of lightly whipped cream; keep extra jam on the side rather than adding more to the bars, which can make them overly sweet.
Variations
For a darker finish, replace the milk-chocolate topping with dark chocolate, or use half milk and half dark chocolate. You can substitute smooth strawberry jam for raspberry, though the result will be sweeter and less tart. To add a little crunch, scatter 25 g (about ¼ cup) of finely chopped toasted hazelnuts over the melted topping before it sets. For a gluten-free version, use a reliable plain gluten-free flour blend in the same quantity; the base may be a little more delicate, so cool it fully and handle the slab carefully. Check ingredient labels if you are avoiding gluten, nuts or other allergens.
Storage and Reheating
Store the cut bars in an airtight container in the refrigerator for up to 5 days, with baking parchment between layers so the chocolate does not stick. Let a portion sit at room temperature for about 10 minutes before serving for a softer, chewier bite. These bars do not need reheating, and microwaving can make the chocolate melt unevenly and the filling runny. For longer storage, freeze the sliced bars in a sealed container, separated with parchment, for up to 2 months. Thaw overnight in the refrigerator, then bring to room temperature briefly before serving.
Frequently Asked Questions
Can I use homemade caramel instead of dulce de leche?
Yes. Use a thick, spoonable caramel sauce, not a thin pouring sauce. A runny caramel can make the filling slip when you cut the bars. If your homemade caramel is loose, chill it until it is thick but still spreadable.
Can I make these bars without Mars bars?
You can use another chocolate-and-nougat bar of a similar size, but the flavour and texture will vary. Avoid replacing them with plain chocolate alone: the nougat is part of what makes the filling chewy. Keep the combined weight close to 150 g.
Why is my chocolate topping cracking?
A thick chocolate layer or a very cold slab can cause cracking during slicing. Let the bars stand for several minutes, and use a warm, dry knife. Adding the small amount of oil specified also makes the topping a little easier to cut.
Can I make them a day ahead?
Yes. Prepare and chill the bars, then cover the pan or store the sliced pieces in an airtight container in the refrigerator. Slice before serving if you want especially tidy edges, and allow a few minutes for the bars to soften slightly.
Can I use fresh raspberries instead of jam?
Fresh berries release juice and will not form a stable layer, so they are not a direct substitute. Use thick raspberry jam inside the bars and serve fresh raspberries alongside instead.
Do these bars need to be kept refrigerated?
For the best texture and to keep the caramel firm, refrigerate them between servings. Do not leave them at room temperature for more than about 2 hours, especially in a warm room; return leftovers promptly to the refrigerator.