Use a bit of the melted butter to lightly coat the bottom and sides of a 9 X 13 X 3-inch baking dish, and set the remaining melted °°°butter aside for later.
Crack the eggs directly into the greased baking dish and use a whisk to gently whip them until they're very smooth.
Now add the half and half, maple syrup, pumpkin, and vanilla and whisk until everything is thoroughly mixed in.
Sprinkle the cinnamon, cardamom, ginger, cloves and salt evenly over the egg mixture and then whisk until they are completely blended in, and the entire mixture is smooth. (If you have an immersion blender, it will blend everything perfectly without splattering -- otherwise, by blending the eggs first, you should achieve the same results.)
Sprinkle about 1 tablespoon of the raisins into the egg mixture, and then begin adding the torn pieces of Challah bread. As you add each piece, gently press it to the bottom of the dish -- it will pop back up, but this will help ensure it absorbs as much liquid as possible.
Once you've added about one even layer of the bread, sprinkle about half of the remaining raisins on top, and then drizzle about half of the melted butter evenly on the surface.
Continue to add more and more of the bread pieces until you've filled every nook and cranny -- pressing them down into the liquid as you go.
Sprinkle the last of the raisins, and drizzle the last of the melted butter evenly over the top, and press everything down a final time. The dish should be quite full so when you add pressure, you should see bits of the liquid rise through the bread and along the edges. This is exactly what you want.
Cover the dish with plastic wrap and place in the refrigerator for at least 2 hours, and ideally overnight.
About 30 minutes before you're ready to bake, preheat the oven to 400°F, remove the baking dish from the refrigerator, place it on a baking sheet, and remove the plastic wrap.
Bake in the preheated 400°F oven until the pudding has become golden brown and has risen a couple of inches, about 35 minutes. Check on it after about 20 minutes, and periodically there after. If the top seems like it’s getting too dark before it's done, cover it lightly with foil for the remaining cooking time.
Once you’ve removed the pudding form the oven, let it rest for about 15 minutes.
Serve warm! (You can make this the day before: Cool it completely, cover and then place it in the refrigerator. Remove it from the refrigerator about an hour before you're ready to serve, and reheat it in a 325°F oven until it's heated through, about 15 minutes.)