This rich, decadent cake is also known as pastel impossible (impossible cake) and for very good reason – the moist chocolate cake and creamy custard layers swap spots (completely!) during baking. The caramel topping traditionally used is cajeta (Mexico’s sugary goat’s milk caramel), but I have used dulce de leche (caramelised sweetened condensed milk) in this recipe, which is far easier to find outside of Mexico!






Skill level

Average: 3.1 (369 votes)


  • melted butter, to grease
  • 300 g (1 cup) dulce de leche



  • 375 ml (1 tin) evaporated milk
  • 395 g (1 tin) sweetened condensed milk
  • 4 eggs
  • 1 tsp natural vanilla essence or extract


Chocolate cake

  • 125 g butter, cubes, at room temperature
  • 165 g (¾cup) caster sugar
  • 1 egg
  • 115 g (¾ cup) plain flour
  • 40 g (⅓ cup) cocoa powder
  • ½ tsp baking powder
  • ½ tsp bicarbonate of soda
  • 185 ml (¾ cup) buttermilk

Cook's notes

Oven temperatures are for conventional; if using fan-forced (convection), reduce the temperature by 20˚C. | We use Australian tablespoons and cups: 1 teaspoon equals 5 ml; 1 tablespoon equals 20 ml; 1 cup equals 250 ml. | All herbs are fresh (unless specified) and cups are lightly packed. | All vegetables are medium size and peeled, unless specified. | All eggs are 55-60 g, unless specified.


Cooling time 3 hours

Preheat oven to 180°C (160°C fan-forced). Brush a non-stick 2.5 litre (10 cup) bundt tin or fluted ring tin with melted butter to grease. Warm the dulce de leche in a small saucepan until a pouring consistency and then pour into the base of the pan. Place the pan in a roasting pan and set aside for the dulce de leche to firm.

To make the custard, place the evaporated milk, sweetened condensed milk, eggs and vanilla in a large bowl and use a balloon whisk to whisk until combined. Set aside while making the chocolate cake.

To make the chocolate cake, use an electric mixer to beat the butter and sugar, scraping down the sides of the bowl occasionally, until pale and creamy. Beat in the egg. Sift together the flour, cocoa powder, baking powder and bicarbonate of soda. Add half the flour mixture to the butter mixture and beat on low speed until just combined.

Add half the buttermilk and beat until just combined. Repeat with the remaining flour and buttermilk in separate batches and beat until just combined.

Spoon the cake mixture into the prepared tin and smooth the surface with the back of a spoon. Slowly and carefully pour the custard mixture over the cake mixture. Add enough boiling water to the roasting pan to reach half way up the side of the cake tin and then cover the tin with foil. Carefully transfer the roasting pan to the preheated oven and bake for 1¼ hours or until a skewer inserted into the cake comes out clean. Remove the tin from the roasting pan and place on a wire rack. Remove the foil and cool the cake in the tin (this will take about 3 hours). 

To serve, use a small palette knife to gently ease the cake form the side of the tin. Place a serving plate over the top of the tin and invert the cake onto it (you may have to shake the tin a little to release it). Serve cut into wedges.


Baker’s tip

• This cake will keep in an airtight container, turned out from its tin, in the fridge for up to 2 days. Stand at room temperature for 30 minutes before serving.


Anneka's mission is to connect home cooks with the magic of baking, and through this, with those they love. Read our interview with her or for hands-on baking classes and baking tips, visit her at BakeClub. Don't miss what's coming out of her oven via Facebook, Twitter, Instagram and Pinterest


Photography by Alan Benson. Styling by Sarah O’Brien. Food preparation by Kerrie Ray.


For more recipes, view our online column, Bakeproof: Latin American cakes.