Cream butter and salt and add sugar and beat until smooth. Add the egg and vanilla and beat until homogenized. Add flour and almond meal and mix to combined. Wrap up and chill completely. On a floured work surface, work the chilled pastry to soften and becomes pliable. Roll out into a 3mm thick sheet. Keep dough cool especially during warm days. Cut into desired shapes. Chill pastry leftovers and make more cookies until done. Lay cookies on tray lined with silicone mat or parchment and freeze. At that point, frozen cookies can be stored in freezer bags for weeks.
Bake frozen cookie at 375ºF/190ºC oven for about 12 minutes or until barely golden brown.
Soak gelatin sheets in cold water and drain; set aside. In a stand mixer fitted with the whisk attachment, beat egg whites and cream of tartar on medium speed. Meanwhile, in a small saucepan bring to boil, water, sugar and corn syrup. Cover and let cook for 5 min. Remove the lid and continue to cook syrup until it reaches 250ºF/120ºC. Remove from the heat and throw in the softened gelatin into the hot syrup. Carefully, pour hot syrup into the foamy egg whites. Increase the speed and beat on full blast until cool - thrown in lemon zests.
Flip half of the baked cookies (face side down) and pipe out the marshmallow filling following the shape of the animal. Cover with the second cookie to stick. Refrigerate cookies. Leftover filling can be saved and spread in a small baking tray lined with a greased plastic wrap. Chill completely and cut into desired shapes. Enjoy!