Whisk gluten-free flour blend, cake flour, salt, and sugar in an electric mixer.
Add cold butter and shortening, mixing until the dough resembles coarse crumbs.
Gradually add ice water as needed, pulse until dough holds together, then form into a disk and chill.
Roll out dough and press into a pie dish, then blind bake until lightly set.
Whisk together pumpkin purée, brown sugar, spices, eggs, and heavy cream in a large bowl.
Pour filling into the prepared crust.
Bake at 350F until the edges are set but the center has a slight jiggle.
Cool completely before garnishing with crumbled Amaretti cookies.