In a mixing bowl, combine the softened butter and sugar. Use a spatula to mix them until you achieve a creamy consistency.
Add the egg to the bowl and mix thoroughly until fully combined with the butter and sugar mixture.
Stir in the sultanas, candied peel, and pine nuts, ensuring they are evenly distributed throughout the mixture.
Pour in the milk and mix to combine. Then, add the vanilla extract, rum, and a pinch of salt. Stir well.
Gradually add the flour and baking powder to the mixture. Begin kneading the dough with the spatula, and once it starts coming together, use your hands to form a ball.
Transfer the dough ball onto a sheet of parchment paper. Press it gently to flatten it to approximately 4 cm in thickness.
Using a knife, score the surface of the dough with the traditional triangle pattern, being careful not to cut too deep.
Preheat your oven to 190°C. Bake the pandolce for 50 minutes, or until the surface is golden and firm.
Remove from the oven and allow the pandolce to cool completely before slicing. Serve with tea, coffee, or as part of a festive spread!