Heat the oven to 190C / 375F. Unroll the puff pastry sheet onto a parchment-lined sheet pan and bake for 18-20 minutes until puffed and deep golden. Cool for 10 minutes, then tear into rough 2-inch pieces. If using croissants, skip this step and tear them directly.
Reduce the oven temperature to 180C / 350F. Butter or lightly oil the 9x13-inch / 23x33cm baking dish.
In the 2-quart / 1.9L saucepan, warm the milk, cream, sugar, vanilla, and cardamom over medium-low heat, stirring until the sugar dissolves. Pull it off the heat as soon as it starts to steam, don't let it come to a boil.
Toast the chopped nuts in the 8-inch / 20cm skillet over medium heat for 3-4 minutes, stirring, until fragrant. Set aside half for the topping.
Scatter the torn pastry pieces evenly in the baking dish. Sprinkle over the raisins, coconut, and half the toasted nuts, tucking some between the pastry pieces.
Pour the warm milk mixture slowly and evenly over the pastry, pressing down gently with a spoon so the top pieces soak up some liquid too.
Scatter the remaining nuts over the top and drizzle with the extra 60ml of cream.
Bake for 20-22 minutes, until the top is golden brown and bubbling at the edges and the custard is set but still soft in the center.
Rest for 5 minutes before serving warm, spooned into bowls.