In a large bowl, place softened butter, vanilla and mix with a hand mixer at medium speed.
Low the speed, add gradually powdered sugar and mix until pale and fluffy.
Incorporate one egg one at a time and mix just until smooth and well combined (don't worry if the mix will lumps at the beginning, it will smooth!).
Sift in flour, salt, baking soda and mix at low speed just until combined: be careful to not overbeat the flour! You can also mix using a spatula to be more gentle.
If you have a piping bag, you can use it (but it isn't needful!): transfer the dough into a piping bag with a 1 cm-0.4 inch round piping tip and pipe wafers onto a baking sheet lined with parchment paper. You have to pipe 3 cm-1,2 inch circles, consider that the wafers will spread in the oven so keep them 4 cm-1,5 inch apart.
If you don't have a piping bag, you can use a teaspoon and spoon the dough onto a lined baking sheet as I show in my recipe video below.
Bake in preheated fan oven at 150°C-300°F for about 12 minutes. If you don't have a fan oven, you have to bake one sheet at a time and increase the temperature at 170°C-340°F.
Let the wafers cool in the baking tray.
