Preheat oven to 350 degrees F. Line a baking sheet with parchment paper or a silicone baking mat.
In a large mixing bowl beat the egg white with the water. Stir in the pecans, mixing well until coated.
In a small bowl, mix sugar, salt, cinnamon, cloves, and nutmeg. Sprinkle over the nuts and mix well to coat them.
Spread nuts onto the prepared baking sheet.
Bake for 30 minutes, stirring every 10 minutes. Be careful not to overcook them!
Using an electric mixer, beat all ingredients in a large bowl until firm peaks form. Set aside 1/2 cup mascarpone cream for the pumpkin filling.
Whisk pumpkin, brown sugar, cream, cinnamon, nutmeg, allspice, and salt in a large bowl to blend. Whisk in reserved 1/2 cup mascarpone cream.
Spread 1/3 cup mascarpone cream over the bottom of an 8x5-inch trifle dish (12- to 14-cup capacity). Place the layer of ladyfingers over cream in the bottom of the dish (about half of the 3-ounce package). Sprinkle 1 1/2 tablespoons rum over. Spread 1/2 cup pumpkin filling over ladyfingers, spreading to edges. Sprinkle 1/3 cup spiced pecans over. Spread 1 cup mascarpone cream over. Cover with another layer of ladyfingers. Sprinkle with 1 1/2 tablespoons rum, then spread 1 cup pumpkin filling over. Sprinkle 1/2 cup spiced pecans over. Repeat 1 more time with 1 cup mascarpone cream, ladyfingers, 1 1/2 tablespoons rum, 1 cup pumpkin filling, and 1/2 cup praline. Spread remaining mascarpone cream over. Cover and chill overnight.
Uncover trifle and sprinkle 1 cup of spiced pecans decoratively over the top.