Sift almond flour, powdered sugar, and pumpkin pie spice together to remove lumps.
Whip egg whites with granulated sugar and cream of tartar until stiff peaks form.
Fold dry ingredients into meringue until batter flows like slow lava.
Pipe small circles onto parchment-lined trays and rest until a thin skin forms.
Bake at 300°F for 15–18 minutes until shells are set and slightly firm.
For ganache: heat cream, pumpkin puree, and spices, then pour over white chocolate and stir until smooth.
For buttercream: beat butter and pumpkin puree, then gradually add powdered sugar and spices until fluffy.
Pipe filling onto one shell and sandwich with another.
Refrigerate overnight to allow flavors and texture to develop.