1. Preheat your oven to 350°F (175°C).

2. Grease two 8-inch (20cm) round cake pans and line the bottoms with parchment paper.

3. Whisk together 250g (2 3/4 cups) of flour and 2g (1/2 teaspoon) of flaky salt in a medium bowl. Set this mixture aside for now.

4. In a large bowl, use an electric mixer to beat 200g (1 cup) of sugar and 2 large eggs until the mixture becomes light and fluffy. This should take about 2 minutes.

5. Add 115g (1/2 cup) of softened butter to the sugar mixture and continue beating until the two are well combined.

6. Whisk together 15g (2 tablespoons) of cocoa powder and 15g (2 tablespoons) of vanilla sugar in a small bowl.

7. Add the flour mixture and cocoa mixture to the sugar mixture, alternating between the two and beginning and ending with the flour mixture. Beat until just combined, being careful not to overmix.

8. Divide the cake batter evenly between the prepared pans and smooth the tops with a spatula.

9. Bake the cakes for 25-30 minutes, or until a toothpick inserted into the center comes out clean. Allow the cakes to cool in the pans for 5 minutes before transferring them to a wire rack to cool completely.

10. To make the caramel topping, combine 120ml (1/2 cup) of heavy cream, 200g (1 cup) of granulated sugar, and 20g (1 tablespoon) of light corn syrup in a medium saucepan. Place the saucepan over medium heat and cook, stirring occasionally, until the sugar has dissolved.

11. Bring the caramel mixture to a boil, then reduce the heat to medium-low and simmer for 5-7 minutes, or until the caramel turns a deep amber color.

12. Remove the caramel from the heat and stir in 55g (1/4 cup) of unsalted butter until melted. Allow the caramel to cool slightly before using it to assemble the cake.

13. To assemble the cake, place one cake layer on a serving plate and spread a layer of caramel topping on top. Place the second cake layer on top of the first and sprinkle with the remaining flaky salt.