Peel the label off the can; place it whole into a large saucepan and cover the can with water (about 2-inches higher than the top of the can. Bring it to the boil, then reduce the heat to the lowest setting on your stove to allow the water to simmer gently for 2 1/2 - 3 hours (or 3 1/2 - 4 hours for a deeper caramel). Using tongs, VERY CAREFULLY turn over the cans halfway through simmering. When the water level begins to reduce down below the top of the cans, top it up with boiled water from a kettle. After simmering, take the saucepan off the heat and allow the can to come to room temperature. (Leave overnight if you have the time). Let them cool completely before opening. Once completely cooled, open the caramel and pour it out into a medium sized bowl. Stir really well.

Preheat oven to 176C | 350F. Cut 4 circles out from each pastry sheet (I used a 12cm | 4-inch round pie cutter). Spoon 1 tablespoon of Dulce De Leche onto one side of each pastry circle; lightly brush each side edge with the whisked egg white; fold each circle over and pinch the pastry at the edges. Fold them over and pinch again to create a 'seal,' Brush the tops over with the remaining egg white; lightly pierce the tops with a fork; place them onto an oven tray lined with baking paper; and bake for 20-25 minutes, or until golden and puffed up.

Allow them to cool for about 5 minutes; brush them over with the melted butter; and evenly coat them in the Cinnamon Sugar mixture. Serve with the Mexican chocolate dipping sauce!

Melt the chocolate and milk together over stove top in a small sauce over gentle heat; or alternatively in the microwave in 30 second increments, until melted. Remove from heat and stir until smooth with a fork until smooth and silky. Stir through the chili powder, vanilla, cinnamon and Nutella (if using), and mix until smooth.