In medium bowl, add cashews and enough hot water to cover; let stand 30 minutes, then drain.
Line 9" springform pan with aluminum foil so that foil extends about 2" over all sides of pan; spray with cooking spray.
In food processor, pulse dates on high until small crumbs remain; transfer to large bowl.
In food processor, pulse carrots, walnuts, flour, vanilla extract, cinnamon and ginger on high until small crumbs remain.
Fold carrot mixture into dates; firmly press in even layer in prepared pan.
In blender, purée cashews, milk and syrup on high until smooth. Pour cashew mixture over carrot mixture; cover and freeze 2 hours.
Using overhanging sides of foil, lift cake out of pan; transfer to cutting board. Remove foil; cut into 16 slices. Serve garnished with walnuts and cinnamon, if desired.
Video
Notes
Leftover cake can be frozen in a freezer-safe airtight container up to 2 weeks.