Preheat oven to 375 degrees. Grease a 12-cup muffin tin pan or line with silicone muffin liners.
Bring a large pot of water to a rapid boil and salt heavily. Cook the elbow noodles according to package directions and then drain well. Place the cooked pasta into a large mixing bowl.
Return the empty pot to the stove and melt the butter over medium heat. Whisk in the flour to form a roux and allow to cook for 1 minute. Slowly whisk in the milk. Bring to a boil and then reduce the heat to medium-low and simmer, whisking constantly, until thickened, about 3-5 minutes. Remove from heat, and stir in the nutmeg, salt, garlic powder, and shredded cheese. Stir until the cheese has melted.
Pour the cheese sauce over the cooked noodles and stir until well incorporated. Add in the whisked egg and pumpkin puree and stir to combine.
Scoop into prepared muffin tin by ¼ cup measurements.
To prepare the topping, mix together the cheese, breadcrumbs, and butter until just combined. Sprinkle evenly over the top of each muffin.
Bake for 10-12 minutes or until muffins set.
Cool for 15 minutes and then remove the muffins from the muffin tin.
Macaroni and Cheese: Feel free to substitute 4 cups of leftover homemade mac and cheese instead of preparing mac and cheese from scratch. Mix the 4 cups of prepared Macaroni and Cheese with ½ cup pumpkin puree and 1 egg and bake as directed. Cheese: It is best to use a yellow cheddar to disguise the pumpkin puree. For the creamiest mac and cheese, grate the cheese yourself. Pumpkin Puree: Use 100% canned pumpkin, not pumpkin pie filling. Feel free to use sweet potato puree, carrot puree, or butternut squash puree in place of the pumpkin puree. Storage: Store cooled muffins in an airtight container for up to 4 days in the refrigerator. To Freeze: Allow the muffins to cool completely and then place them onto a baking sheet and freeze until solid. Place individually frozen muffins into a freezer bag. Store in the freezer for up to 3 months. Grab a couple of muffins from the freezer in the morning and pack in lunch--the muffins will defrost by lunchtime. OR heat individually in microwave for 1-2 minutes and store in a thermos for school lunches.