Preparation Steps

• Line an 8x8-inch square pan with parchment paper, leaving an overhang on two sides to help lift the cake out later. Arrange a single even layer of cocoa biscuits across the base; break a few cookies to fill any small gaps.
• Whip the mascarpone, cold heavy cream, sweetened condensed milk, and vanilla in a large bowl. Start on low speed, then increase to medium-high and beat until the mixture thickens to soft peaks and is smooth (about 2–3 minutes by electric mixer). Scrape down the bowl once or twice.
• Spread about half of the mascarpone cream evenly over the first cookie layer, using an offset spatula to make a flat surface. Press a second layer of biscuits gently into the cream so they sit snugly.
• Warm the dulce de leche briefly in a small saucepan or microwave until it’s fluid and easy to spread (about 20–30 seconds in the microwave). Spoon and smooth the dulce de leche over the second biscuit layer in an even coat.
• Add a third layer of cookies on top of the caramel. Spread the remaining mascarpone cream over that final cookie layer, smoothing the top neatly. Tap the pan on the counter to settle the layers and remove air pockets.
• Toast the chopped hazelnuts in a dry skillet over medium heat for 3–4 minutes, stirring often, until fragrant and lightly browned. Transfer to a small bowl to cool so they don’t overcook in the residual heat.
• Place the chopped dark chocolate in a heatproof bowl with a tablespoon of cream or water and melt gently over a pan of simmering water (double boiler) or in short bursts in the microwave, stirring until glossy. Fold the toasted hazelnuts into the melted chocolate, then pour the mixture over the chilled cream layer and spread to the edges.
• Scatter the chopped Kinder Max King pieces across the chocolate while it is still warm so they stick, and finish with a light sprinkle of extra chopped hazelnut if desired. Cover the pan with plastic wrap and chill in the refrigerator for at least 3 hours (or overnight) until firm.
• When fully set, lift the cake from the pan using the parchment overhang. Place on a cutting board and slice into 9 squares with a sharp knife, wiping the blade between cuts for clean edges. Serve chilled or at cool room temperature.