Heat the oven to 350ºF. Spread the chopped pumpkin pieces out onto a lightly greased baking sheet and cover with foil. Bake the pumpkin for 1 hour, until soft. Using a blender, purée the pumpkin until smooth. (You will only need 1 cup of the purée for this recipe. The remaining pumpkin can be frozen for later use for up to 3 months.)
Preheat the oven to 400ºF. In a bowl, mix flour, brown sugar, baking powder, pumpkin pie spice, and a pinch of salt.
Add the eggs, oil and pumpkin purée to the dry ingredients.
Add the oats and cranberries and mix well.
You can either grease individual muffin silicone cups or place muffin liners in a muffin pan and scoop the batter in. Sprinkle some more oats and cranberries on top. Bake for 15 to 20 minutes, or until you insert a toothpick in the center and it comes out dry. Let cool.