In a mixing bowl, blend the sugar, eggs and yolks, half-and-half, whipping cream and vanilla to make a custard mixture.
Mix the pumpkin with the cinnamon, nutmeg and 1/2 cup of the custard mixture.
Slice the bread into half-inch-thick slices.
Coat the insides of two 10-inch cake pans with a generous amount of butter. Line the perimeters with the smallest slices of bread, then cover the bottom with an overlapping bread layer. Pour enough custard mixture over the bread to soak it.
Spoon a quarter-inch layer of the pumpkin mixture and about a third of the pecan pieces across the bread. Add another layer of bread, soak it with the custard mixture, and top with the remaining pumpkin mixture and another third of the pecans. Finish with another layer of bread and pecans, and a final soaking with the custard. Repeat this procedure for the other pan.
Bake in the preheated 250-degree oven for about an hour and a half. The pudding will rise a great deal, but it will fall again when you take it out of the oven. Remove and cool.
