Heat oven to 350°. Generously butter and flour a 9-inch spring-form pan. Combine all the dry ingredients in a bowl and stir them together with a whisk to blend.
Cream the butter on high with the sugar until light and fluffy. Lower the speed and slowly pour the syrup into the butter mixture, then add the vanilla. Add the eggs one at a time, beating until each one is well incorporated and scraping down the bowl between additions. When well blended, stir in the squash.
With the mixer on low, add the flour mixture in ½ cup increments until all is incorporated. Remove the mixing bowl and using a large rubber scraper, give the batter several turns, scraping along the sides and bottom of the bowl, to make sure all the flour has been incorporated. Finally, add the dates to the batter. Scrape the batter into the pan and even out the surface.
Bake in the middle oven until firm and springy and a cake tester comes out clean, 1 hour to 1 hour and 10 minutes. When mostly cool, release the rim and carefully transfer the cake from the pan onto a cake plate. Serve slightly warm or at room temperature, plain, frosted with the cream cheese icing, or with ice cream and apple caramel or maple syrup.
Winter Squash Spice Cake variation (add to the dry ingredients)
1 teaspoon cinnamon, ½ teaspoon nutmeg, ¼ teaspoon allspice and 1⁄8 teaspoon powdered cloves.