Line a large cookie tray or roasting pan with foil.
Toss the squash in olive oil and brown sugar.
Spread out in a single layer in the prepared pan and sprinkle with a little salt.
Roast 30-40 minutes until squash is soft and easily pierced with a fork.
Let cool and then puree in a blender or food processor.
For the Muffins
Preheat oven to 350 degrees.
Grease or line a 12-muffin tin.
Put the flour, spices, salt and baking powder in a bowl and stir them together with a whisk or fork.
Cream together the butter and sugar on medium speed in a mixer until the mixture is soft and fluffy. It will lighten in color and become smooth. (about 2-3 minutes).
Beat in the eggs, one at a time.
Add the pumpkin and vanilla and beat until well combined.
On low speed add the flour and spice mixture.
When the flour is almost combined add the dried fruits. Mix until just incorporated. Be carefully not to overmix this.
Fill the muffin tins equally, about ¾ full.
Sprinkle the muffins liberally with demerara sugar.
Bake 18-20 minutes until the tops bounce back when touched and a toothpick inserted into the center comes out clean (or barely crumbed).
Let muffins cool ten minutes and then turn out to dry on a rack.
Recipe Notes
Squash can be prepared ahead and refrigerated or frozen until needed.