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–+ servings
Slices of chocolate biscuit cake.

Marbled Chocolate Biscuit Cake

Buttery shortbread fingers, roasted hazelnuts (if you’re a Cadbury Whole Nut fan, you’ll love this!), the salty snap of chocolate-coated pretzels and a triple-chocolate marble that looks far fancier than it really is.
The method for these crunchy chocolate no-bake bars is blissfully simple: Melt, mix, press, chill.
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Course: Dessert, Snack
Cuisine: British
Prep Time: 15 minutes
Cooling time: 1 hour 30 minutes
Total Time: 1 hour 45 minutes
Servings: 16 squares
Calories: 411kcal
Author: Maretha Corbett

Equipment

  • 8" x 8" (20cm x 20cm) square baking tin

Ingredients

For the biscuit cake base

  • 225 grams (7.9 oz) milk chocolate
  • 125 grams (4.4 oz) butter - salted or unsalted
  • 125 grams (4.4 oz) golden syrup
  • 300 grams (10.6 oz) shortbread fingers - or other cookies of choice like graham crackers/digestives/oaty cookies
  • 90 grams (3.2 oz) chocolate-covered pretzels - Like 'Flipz'
  • 150 grams (5.3 oz) hazelnuts, roasted

For the marbled topping

  • 80 grams (2.8 oz) milk chocolate
  • 80 grams (2.8 oz) dark chocolate
  • 80 grams (2.8 oz) white chocolate

Instructions

Make the cake base

  • Line a 20 cm × 20 cm (8″ × 8″) square tin with parchment paper, leaving a slight overhang for easy lifting later.
  • In a microwave-safe bowl, gently melt the milk chocolate, butter and golden syrup in 30-second bursts, stirring between each.
    Stop when almost melted and stir until smooth. Overheating can cause the mixture to split.
    225 grams (7.9 oz) milk chocolate, 125 grams (4.4 oz) butter, 125 grams (4.4 oz) golden syrup
  • Let it cool for 5–7 minutes so it doesn’t melt the chocolate pretzels. In the meantime, get on with the rest.
  • Roughly chop the shortbread fingers, chocolate-covered pretzels and roasted hazelnuts (leave many hazelnuts whole for texture).
    Don’t chop the pretzels too finely, as you want chunky bits for added crunch.
    300 grams (10.6 oz) shortbread fingers , 90 grams (3.2 oz) chocolate-covered pretzels, 150 grams (5.3 oz) hazelnuts, roasted
  • Pour the slightly cooled chocolate mixture over the chopped biscuits, pretzels and nuts.
  • Stir gently until everything is evenly coated.
  • Spoon the mixture into the prepared tin. Press it down firmly with the back of a spoon or the base of a glass to remove air gaps and create an even layer (firm compression prevents crumbly slices later).
  • Chill for 1 hour at room temperature, then 30 minutes in the fridge.
    This gentle set prevents the topping from cracking later.

Add the marbled topping

  • Place the milk, dark and white chocolate in three separate microwave-safe bowls.
    Melt each one individually in 15–20 second bursts, stirring between each burst so the heat distributes evenly.
    Stop when there are still a few small lumps and stir until smooth. The residual heat will finish melting them. This prevents scorching and keeps the chocolate silky.
    (Alternatively, melt each chocolate in a heatproof bowl set over a pan of barely simmering water, stirring gently.)
    80 grams (2.8 oz) milk chocolate, 80 grams (2.8 oz) dark chocolate, 80 grams (2.8 oz) white chocolate
  • Remove the tin from the fridge and let it sit at room temperature for about 10 minutes. This prevents the topping from seizing or cracking against a very cold base.
    Working quickly, dollop spoonfuls of each melted chocolate randomly over the surface.
    Gently spread each blob so they all touch (no gaps!), then give the tin a light shake to level.
  • Drag a skewer or toothpick through the blobs in random swirls to create a marbled effect.
    Refrigerate for 30 minutes or until firm.
  • Lift out using the parchment overhang.
    Use a sharp, hot knife (dip in hot water, wipe dry) to slice into neat squares, wiping between cuts to prevent cracks or crumbs.

Notes

Top tips for the perfect chocolate biscuit cake

Avoid split chocolate

Use gentle heat only when melting the butter, syrup and chocolate.
Overheating causes the fats to separate, leaving a greasy layer on your bars.
Stop melting when a few lumps remain and then stir until smooth. The residual heat will finish the job.

Let it set at room temperature first

Putting the tin straight into a cold fridge can shock the chocolate-butter mixture, making the fats set unevenly and leaving greasy patches.
Let it firm up at room temperature for an hour, then chill it briefly to finish setting. This gives a smoother, cleaner texture.

Prevent cracks in the topping

If you pour warm melted chocolate onto a rock-hard, fridge-cold base, the sudden temperature difference can make the topping seize or crack.
After chilling, let the base stand at room temp for 5–10 minutes before adding the marble topping.

Stop slices from crumbling

When pressing the mixture into the tin, compress it firmly with the back of a spoon or a glass.
A well-packed base slices neatly and won’t fall apart.

Get bakery-worthy cuts

Use a large, sharp knife, dipped in hot water and wiped dry between cuts. Slice straight down (don’t saw) for crisp, professional-looking squares.
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**Nutritional data disclaimer**

Please keep in mind that the nutritional information provided below is calculated by a third party and we cannot guarantee the accuracy. We try our best to give you the most accurate information, but we do not take responsibility for errors that may be present. Also, the nutritional value of the recipe may change depending on the exact brands and products used. We recommend that you consult with a qualified healthcare professional or registered dietitian for personalised advice on your dietary needs.

Nutrition

Calories: 411kcal | Carbohydrates: 41g | Protein: 4g | Fat: 27g | Saturated Fat: 12g | Polyunsaturated Fat: 3g | Monounsaturated Fat: 10g | Trans Fat: 0.3g | Cholesterol: 18mg | Sodium: 195mg | Potassium: 200mg | Fiber: 3g | Sugar: 25g | Vitamin A: 217IU | Vitamin C: 1mg | Calcium: 35mg | Iron: 2mg
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