Pre heat the oven to 375°. 

Toss the butternut squash with the vegetable oil and roast for 60 to 70 minutes, tossing occasionally until the edges are starting to brown and the chunks are very tender. 

Set aside to cool 10 minutes or so

Turn oven down to 350°. 

Puree the butternut squash in a food processor. You should get approximately 2 cups. 

Grease and flour a 12-cup Bundt pan. Flour (or spray with a floured cooking spray)

In a medium bowl combine the flour, baking powder and soda, salt, cinnamon, and ground coriander. Set aside. 

In a mixing bowl, cream the butter with the sugar and brown sugar until very light and creamy.

Add in the eggs, one at a time beating well and scraping down the side of the bowl after each addition. 

Beat in the orange rind, vanilla and the pureed butternut squash. 

At low speed stir in the flour mixture. Continue mixing just until the flour has been incorporated. You can mix in the flour by hand using a large spatula. 

Spread the batter in to the prepared Bundt pan, smoothing out the batter evenly.

Bake for 55 to 65 minutes or until a cake tester or wooden toothpick inserted in the center comes out clean. 

Cool for 15 minutes in the pan, and then invert onto a rack and cool completely. 

Dust with powdered sugar and serve drizzled with the caramel sauce. Or serve the sauce on the side.