Pour the coconut rum into a shallow dish. Dip each ladyfinger into the coconut rum for about 2-3 seconds, then arrange half of them in a layer at the bottom of a baking dish.

In a bowl, combine 1 cup of granulated sugar and 1/4 cup of cocoa powder, whisking until blended. Gradually drizzle in 1/2 cup coconut rum, stirring until smooth.

In a large bowl, whip 2 cups of cold whipping cream and 1 cup of mascarpone cheese together on medium-high speed until stiff peaks form.

Carefully fold the whipped cream mixture into the cocoa base until smooth without deflating.

Spread half of the creamy chocolate mixture over the layer of ladyfingers, smoothing it out evenly.

Add a layer of the remaining whipped cream mixture on top, then sprinkle with toasted coconut and chopped pecans.

Repeat the layering with the rest of the ladyfingers and cover with the remaining chocolate mixture. Cover with plastic wrap and refrigerate for at least 3 hours.