There are lots of ingredients and lots of steps here, but these are great for a special occasion such as a company breakfast. The sugar content is pretty high for a muffin, clocking i at 18.5 grams with the topping, so you wouldn't want to eat more than one on the 25-gram-limit program, but one is pretty satisfying.
Mis topping ingredients together with your fingers.
Line a baking sheet with a triple layer of paper towels, spread the pumpkin puree on them, then put another two layers of paper towels on top, and press firmly on those top towels. They will quickly become saturated with moisture. You'd think that you'd end up with a total mess and have to scrape the pumpkin off the towels, but it just peels right off. You'll then need to measure the drained pumpkin to make sure you haven't removed too much moisture; you want it to measure 1 1/2 cups.
Plop the pumpkin into a bowl and mix in the granulated sugar, brown sugar, oil, and cream cheese until combined and there are no traces of cream cheese. Whisk together eggs and buttermilk (or water, if you're using the powder). Add egg mixture to pumpkin mixture and whisk to combine. (But--I'm not sure this whole extra whisking step is necessary, and now you have yet another dirty bowl. Just put the eggs and buttermilk or water in the bowl with the pumpkin and mix it, for heaven's sake!) Fold flour mixture into pumpkin mixture until combined (some small lumps of flour are OK). Fold walnuts into batter, if using.
Scoop batter into prepared pans. Sprinkle topping evenly over top of each muffin. Bake until toothpick inserted in center comes out clean, 15-20 minutes. Rotate those pans, even if you have a convection oven. I was able to bake four pans at once (so a double recipe) even though my oven door didn't quite close. Let muffins cool in pans on wire rack for 5-10 minutes before removing from pans. Serve warm or at room temperature.
Good with cream cheese.