Preheat oven to 350°F.
To prepare the crust, place crumbs, 3 tablespoons coconut sugar and butter in a small bowl, tossing with a fork to combine. Use the bottom of a small glass to evenly press mixture into bottom and up sides of a 10-inch tart dish (see Note) coated with cooking spray. Bake for 10 minutes. Set aside.
To prepare the filling, combine pumpkin, 3/4 cup coconut sugar, half-and-half, flour, pumpkin pie spice, vanilla, salt and eggs in a blender. Blend until smooth. Pour into prepared crust. Bake 35-40 minutes, or until filling is set. Cool completely on wire rack.
Place cream and maple syrup in a medium bowl. Beat with a mixer until stiff peaks form. Dollop or pipe whipped cream onto cooled tart. Dust with pumpkin pie spice, if desired. Sprinkle with walnuts.