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Millionaires Shortbread Cake with caramel and chocolate sauce with a slice cut out on a plate in front
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Millionaire Cake

Millionaire's Shortbread Cake is a fantastic riff on its namesake bar. Layers of brown sugar sponge cake are piled full of caramel sauce, chocolate ganache and homemade shortbread. Who wants seconds?
Prep Time2 hrs
Cook Time35 mins
Total Time2 hrs 35 mins
Course: Dessert
Cuisine: American, British, Worldwide
Servings: 8
Calories: 952.87kcal

Equipment

  • 3 x 6 inch cake tins

Ingredients

For the Caramel Sauce

  • 100 g Caster sugar
  • 30 g Butter
  • 90 ml Double (heavy) cream
  • 1/8 tsp Salt

For the Shortbread

  • 30 g Butter
  • 30 g Plain (all purpose) flour
  • 15 g Cornflour (cornstarch)
  • 15 g Caster sugar
  • Pinch salt

For the Chocolate Ganache Sauce

  • 30 g Chocolate see notes
  • 45 ml Double (heavy) cream

For the Cake

  • 180 g Butter - softened
  • 180 g Light brown sugar
  • 180 g Plain (all purpose) flour
  • 1 1/2 tsp Baking powder
  • 3 Eggs - large, free range
  • 3 tbsp Milk (whole/ full fat)
  • 1 tsp Vanilla extract

For the Italian Meringue Buttercream

  • 3 Egg white (large, free range)
  • 1/8 tsp Cream of tartar
  • 240 g Caster sugar
  • 70 ml Water
  • 300 g Butter (softened)

Instructions

Make the Caramel Sauce

  • Make the caramel by putting the caster sugar (in an even layer) in a heavy-based saucepan and let cook over a moderate heat, swirling around the pan a couple of times to cook evenly. The sugar should first melt, then turn a lovely amber colour
  • Once the sugar has dissolved and the colour is deep amber, carefully add the butter & cream. Take care as the mixture may bubble up. Don't worry if the caramel solidifies in places. Put the pan back on a gentle heat and cook for around 2 minutes more, stirring frequently until it is smooth. Do not let the caramel boil
  • Meanwhile, grind the sea salt in a pestle and mortar
  • Take the caramel off the heat and stir in the salt then set aside to cool to room temperature (at least 6 hours, preferably overnight - cover once cool)

Make the Shortbread

  • Preheat the oven to 150C/ 300F/ Gm2 and line a baking sheet with parchment paper
  • Put the flours, sugar & salt into a bowl & stir briefly
  • Cube the butter, add to the bowl and toss
  • Next, rub the butter into the dry ingredients. It will at first resemble sand but keep rubbing until the dough begins to bind
  • Form into a ball and knead very briefly before rolling out to around 2mm thickness
  • Cut small circles out - I used a cutter measuring approx 2 1/2 cm
  • Reroll the dough to get a few more circles until you have around 30 shortbread cookies
  • Lay the cookies on the parchment at least 1 cm apart, chill for 30 minutes and then bake for 15-20 minutes until beginning to turn golden
  • Set aside to cool completely then store in an airtight container until reader to assemble the cake

Make the Chocolate Ganache

  • Chop the chocolate finely and place in a small heatproof bowl
  • Heat the cream to scalding, but not boiling and pour over the chocolate
  • Let sit for 1 minute then stir until smooth
  • Set aside to cool

Make the Brown Sugar Sponge Cakes

  • Preheat the oven 170C/ 325F/ GM3 and grease & line 3 x 6 inch sandwich cake tins with parchment
  • Using electric beaters, beat the butter and sugar together until light and fluffy
  • Briefly mix the eggs in a jug and gradually add a tsp at a time into the creamed butter & sugar, beating well in between each addition (adding the egg really slowly reduces the risk of the mix splitting)
  • Add the vanilla extract and milk, then beat again
  • Sift the flour and baking powder into the bowl and gently & briefly fold in half using a large metal spoon (about 8 turns of the spoon). Add the rest of the flour and continue to fold in until all ingredients are throughly combined. Take care not to overwork the batter though
  • Divide between the baking tins and bake for approximately 20-23 minutes
  • Test that the cakes are baked through by poking a cocktail stick into them - if it comes out clean then the cakes are ready. If not, return to the oven for a couple more minutes, then test again
  • Once out of the oven remove from the baking tins and allow to cool completely on a wire rack

Make the Italian Meringue Buttercream

  • Put 200g sugar and the water into a medium saucepan then place on medium-low heat and cook until the sugar dissolves. Keep the syrup on a low heat while you prepare the egg whites, then, when the meringue reaches the soft peak stage, raise the heat and cook until the syrup reaches a temperature of 115C (240F)
  • Beat the egg whites and cream of tartar in the bowl of a stand mixer. Add the remaining 40g of sugar spoonful by spoonful and then keep beating until soft peaks form.
  • When the temperature of the sugar syrup reaches 110C (230F) beat the meringue on high until the stiff peak stage
  • Once the syrup reaches 115C (240F) drizzle it slowly into the stiff egg whites whilst the mixer is still running. Take care to pour the syrup into the side of the bowl directly onto the meringue and not onto the metal whisk (to avoid the risk of the incredibly hot syrup splattering you)
  • Continue to whip the meringue until it is lukewarm
  • Switch to a paddle attachment. Add room temperature butter into the running mixer one tablespoon piece at a time then add 60ml of the caramel sauce (cold) to the buttercream
  • Beat until everything is combined and the mixture has reached a silky consistency

Assemble the cake

  • Place 1 layer of cake on a plate/ stand and pipe buttercream over it 
  • Drizzle 1 tbsp caramel sauce and 1 tbsp chocolate ganache over the buttercream. break up 5 shortbread cookies into pieces and scatter over the top
  • Place another layer of sponge on top and repeat
  • Top with the final layer of sponge cake
  • Use some icing to cover the top and side of the cake - a naked cake looks wonderful here
  • Pipe a thin circle of buttercream onto the top of the cake about 1 1/2 cm in from the edge. This will act as a barrier and prevent the caramel and chocolate running into each other
  • Drizzle caramel sauce around the edge of the cake, ensuring that it reaches the buttercream barrier and begins to drip down the side of the cake. Use either a squeezy bottle or a piping bag and nozzle to achieve this
  • Fill the centre section with chocolate ganache and use a small palette knife to spread it to the barrier. Do not overfill the centre with ganache, otherwise, it will flood over the buttercream barrier
  • Pipe buttercream rosettes over the top to hide the buttercream barrier and top each rosette with a shortbread cookie
  • Best served on the day it is assembled. Can keep for up to 3 days but expect the shortbread to soften and loose its crunchy texture

Notes

For the chocolate ganache sauce, the type of chocolate used is up to you. Dark chocolate works well for a less sweet flavour and milk chocolate can be pulled off well too. Can't decide - do as I did and use a 50:50 mix of the 2.
Personsally I would not recommend white chocolate - it comes across a little too sweet in this instance in my view.
Can I make this cake ahead of time?
If assembled too far in advance the cookies in this cake will soften. For this reason, it is best assembled on the day it is intended to be eaten. However, all componenets can be made ahead of time and assembled later - freeze the sponge cake layers  if made more than 24 hours in advance to maintain their freshness. 

Nutrition

Calories: 952.87kcal | Carbohydrates: 91.6g | Protein: 7.11g | Fat: 64.12g | Saturated Fat: 39.87g | Cholesterol: 229.62mg | Sodium: 576.02mg | Potassium: 212.31mg | Fiber: 0.92g | Sugar: 68.38g | Vitamin A: 2023.99IU | Calcium: 89.15mg | Iron: 1.83mg