Beat eggs with sugar and salt until fluffy about 5-10 minutes. Add softened butter (can be combined in equal proportions vegetable and butter)
Add to the bulk of the cream and mix.
Mix the sifted flour, baking powder, zest. Mix the "liquid" and " dry " parts. Stir at a slow mixer speed or with a silicone spatula until evenly combined.
Leave for forty minutes or longer. Can be to leave and on night.
Spread out in paper capsules enclosed in prepared cupcake molds and fill them with dough no more than 2/3, sprinkle with sugar. Bake first at high temperature (220 degrees) for about 10 minutes, then at 190 degrees until tender.