One hour before assembling, tear the Challah by hand into varying sizes of between 1-inch and 2-inch pieces. Spread out on a baking sheet or other surface and allow the bread to begin to dry out. Butter a 13 by 9 by 2-inch baking dish liberally with 2 tablespoons of unsalted butter. Set aside.
Combine 1 cup of water and brown sugar in a heavy saucepan. Bring to a boil over high heat, stirring until the sugar completely dissolves. Reduce heat slightly and boil gently so as not to burn. Reduce to 1 cup, about 10 minutes. Remove from the heat and whisk in 2 tablespoons of the cream and cinnamon. Keep the syrup warm. NOTE: the syrup can be made one day ahead, cooled completely, then covered and refrigerated until ready to serve. To re-warm, remove from refrigeration and pour syrup into a non-stick saucepan. Heat over medium-low heat, stirring occasionally, until the syrup is warmed through.
Arrange the bread pieces in prepared dish. Using a 1-cup dry measure, scoop a mixture of the dried and/or glacé fruits and nutmeats and toss together with the torn bread. Ensure the fruits are well distributed.
In a large bowl, whisk together eggs with remaining 1 cup heavy cream and whole milk. To the egg mixture add vanilla extract, pumpkin puree, pumpkin pie spice, granulated sugar, and the remaining fruits and nutmeats and whisk thoroughly. Pour over the Challah. Gently submerge the peaks of Challah momentarily to soak completely. All of the pieces of bread should be thoroughly soaked.
Let stand for 30 minutes, occasionally pressing the bread cubes into the custard mixture. NOTE: if making ahead, allow to stand for 30 minutes at room temperature pressing the bread pieces into the custard mixture to re-soak every so often. Cut a piece of aluminum foil large enough to fit the baking dish. Spray with cooking spray and cover the baking dish. Refrigerate up to 24 hours. Remove from refrigeration 1 hour before baking.
Preheat the oven to 350°F. Place the pudding on the center rack and bake until it puffs and is set in the center, about 45 to 55 minutes. Pudding is done when center springs back slightly when pressed.
Cool slightly before spooning the bread pudding into shallow dessert bowls. Drizzle with the warm cinnamon syrup.
Optional: serve with a generous scoop of French vanilla bean ice cream. Toast and chop additional pecans if desired and garnish.