I make this so many times throughout the fall and winter months. I roast a large kabocha squash ahead of time and portion it out specifically for this cake and keep them in the freezer so I can make it when the mood strikes.
Adapted from Aran Goyoaga
Roast the squash:
1. Preheat the oven to 400°F. Cut the squash in half and place it on a baking sheet cut-side down. Bake for 45 minutes or until flesh is tender when pierced with a knife or fork. Set aside until cool enough to handle.
2. Scoop out the seeds from the roasted squash and discard. Scoop the flesh into a bowl. Measure out 225g and add to a large bowl for the cake and then subsequent 225g portions to freeze.
Make the cake:
1. Reduce heat to 350°F. Grease the inside of a 9x5 inch loaf pan with olive oil. Cut a long strip of parchment paper and fit it into the pan crosswise leaving a bit of overhang so you can easily lift the cake out of the pan.
2. In the large bowl with the 225g squash, mash it with a fork and then add the sugar, maple syrup, eggs, and olive oil and whisk until smooth.
3. Add the remaining dry ingredients and whisk until it comes together into a thick batter. Pour into the prepared pan and smooth out the top with your spatula.
4. Sprinkle the top with pumpkin seeds if desired.
5. Bake the cake for about 60 minutes until a toothpick inserted in the center comes out clean. Let the cake cool in the pan completely, then lift out and serve.