Start by making the salted caramel. Place the sugar in a saucepan over medium heat and allow it to melt slowly, stirring occasionally, until it turns into a smooth amber caramel.

Carefully add the butter and whisk until fully melted and combined.

Slowly pour in the heavy cream while whisking continuously. The mixture will bubble vigorously at first.

Continue stirring until the caramel becomes smooth and glossy. Remove from heat and mix in the vanilla extract and a pinch or two of salt if desired.

Allow the caramel to cool slightly while you prepare the tiramisu.

In a large bowl, whisk the egg yolks and sugar together until pale and thick.

Add the mascarpone, vanilla extract, and rum, then mix until smooth and creamy.

In a separate bowl, whip the heavy cream until soft peaks form.

Gently fold the whipped cream into the mascarpone mixture.

In another clean bowl, beat the egg whites until stiff peaks form.

Carefully fold the egg whites into the mascarpone mixture to create a light, airy mascarpone cream.

Pour the cooled coffee into a shallow bowl.

Quickly dip each ladyfinger into the coffee and arrange them in a single layer in your serving dish.

Spread half of the mascarpone cream evenly over the ladyfingers.

Add another layer of coffee-soaked ladyfingers.

Spread the remaining mascarpone cream evenly over the second layer.

Pour the salted caramel over the mascarpone layer and gently spread it across the top.

Cover and refrigerate for 4–6 hours so the tiramisu sets and the caramel layer firms slightly.

Before serving, optionally sprinkle the top with flaky salt for a sweet-salty finish.