Marbling is my favourite way to decorate biscuits because it requires no piping, precision or skill and the results are beautiful. These heart shaped biscuits are really simple to make with only 3 ingredients to create a light, buttery shortbread base. Dipped into an easy royal icing mix swirled with food colouring to create a stunning marbled design.
This recipe is also available as a step-by-step video cookalong, showing you how to make and bake the shortbread biscuits, how to create the perfect royal icing consistency and how to achieve a 'marbled' effect on Supper Club's membership platform.
Total time to make : 20 minutes (+ 30 minutes chill time)
Time to bake : 15 minutes
Makes : 24 (depending on cookie cutter size)
Ingredients
Shortbread cookie base
250g butter, softened
125g caster sugar
350g plain flour
Marble Icing
I use this pre-mix royal icing (just add water)
Food dye - I used red and pink gel concentrate*
Heart cookie cutter, mine is about 6.5cm
Method
Cookies
Line two baking sheets with baking paper and set to one side.
In a mixing bowl, beat the butter with an electric mixer for 1 - 2 minutes until pale and fluffy. Add in the sugar and mix again until combined.
Add in the flour and mix together until it starts to form a dough. I find using my hands in the final stages really helps bring it together into a dough ball. Don’t worry if it’s a little crumbly to start with, it will come together after a few minutes of kneading.
Lightly flour a worktop surface (or use a silicone pastry mat*) and tip out the dough. Roll the dough out with a rolling pin until it's about 1cm thick. Dust the cookie cutter with flour and cut out shapes, placing the cut shapes onto the prepared baking sheets. Bring the excess dough together into a ball using your hands, then continue to roll out the dough and cut out shapes until you have no dough left. Place the cut shapes on the baking sheets in the fridge to chill for at least 30 minutes*.
Pre-heat a fan oven to 160ºC. Once chilled, bake for 15 minutes (depending on size, smaller shapes will bake quicker) until the biscuits are only just starting to turn golden around the edge. Remove from the oven at this stage, they’ll continue to bake on the hot baking sheets outside the oven.
As soon as you take the biscuits out of the oven, use the back of a fork to gently 'comb' over the top of the biscuit to smooth out any air bubbles. Transfer them to a wire cooling rack and leave to cool completely before decorating.
Marbling
Sieve the pre-mixed royal icing powder into a mixing bowl and add in water according to packet instructions. Use a spoon to mix everything together, adding more water (1 tsp at a time) as required until you achieve the right consistency (see notes below). This will be the white ‘base’ colour.
Spoon a few tablespoons of the white base mixing into a separate small bowl, add in 1/2 tsp of the red food dye and mix together well. Add in more food dye, a few drops at a time if needed, until you're happy with the colour. Then, spoon this into a piping bag (no need for a nozzle) or ziplock bag.
Repeat this step with the pink food dye in another separate bowl, filling a separate piping bag.
Spoon the remaining white base mixture into a clean, shallow bowl, this makes the dipping technique a lot easier than using a big mixing bowl. Be sure to cover your icing bowl with a damp tea-towel to keep the icing from drying out, which can happen quickly, if you’re leaving it on the side for more than a few minutes.
Snip off the tip of the piping/ziplock bag from the red and pink coloured icing and pipe some of the coloured icing onto the white base in a zig-zag pattern. Then, use a cocktail stick or the end of a teaspoon to 'swirl' them together to create a marble effect.
Take a baked biscuit shape and lightly drop it, face down, into the marble mixture. Don’t move the biscuit around but use fingertips to tap and press it into the icing, covering it to the edges. Use your fingers to ‘peel’ the biscuit off (like you’re peeling a sticker off an apple) rather than lifting it straight up. Gently shake and wiggle the excess icing off and then flip the biscuit over, placing it back on the cooling rack to let any excess icing drip off. Don’t worry if it has an icing ‘tail’, this will sink in and even out as it settles and dries. Use a cocktail stick to pop any air bubbles that have formed in the icing and gently move and smooth any icing gaps. Do this as soon as you can as the icing will start to set within a few minutes.
Repeat, re-piping the zig-zag dyed icing and re-swirling them to refresh your marbled effect (step 4) every 3 - 4 biscuits.
Leave iced biscuits to air dry for a few hours to let the icing completely set (overnight at room temperature is best).
Nutritional Information:
(per iced biscuit)
210 cals
7g fat, 36g carbs, 2g protein
Good to know
Use a gel concentrate food dye rather than a watery, liquid one. These tend to be more pigmented so you need a lot less for a vibrant colour and it doesn't loosen the royal icing consistency as much.
I use and love a silicone pastry mat for all dough work including these biscuits. It stops the dough from sticking to work surfaces, meaning you need a lot less flour to 'dust' the surface and it makes washing up much easier.
Chilling the biscuits in the fridge before baking them helps to stop them from spreading in the oven and is especially important for more intricate shapes. You can also flash freeze them for 10 minutes instead.
The consistency we're looking for with the royal icing is like 'toothpaste'. The icing needs to be thick enough to coat the cookie but soft enough to flow off, not a thick paste.
The best way to test this is to look at the icing ‘tail’ your mixture creates. Use the end of a spoon to dip into the icing then pull it out and draw a figure of 8 shape on the surface. It should take 4 - 6 seconds before the tail sinks back in.
Unbaked biscuit dough can be frozen in a dough ball wrapped in cling film and placed in an airtight container or ziplock bag for up to 3 months. Defrost overnight in the fridge before rolling out.
Freeze cut biscuit shapes (end of step 4) in an airtight container with baking paper to separate them for up to 3 months. Bake from frozen, adding 2 minutes to the bake time.
Store iced biscuits for 3 - 4 weeks in an airtight container at room temperature. The long shelf life makes these great for gifting or posting.
Vegetarian.