Collect together your equipment (see Recipe Notes below) and ingredients.

Preheat oven to Fan Oven 160°C/180°C/350°F/Gas 4

Beat the butter, sugar and salt together with an electric whisk.

Add the condensed milk and beat again.

Add the flour, baking powder and lemon zest and fold into the cookie dough.

Use a small ice cream scoop or a 1 tablespoon measure to divide the mixture into balls – you should make around 16 – 18 cookies.

Place spread out on a baking sheet - I cook 6 per sheet but it depends on the size of the baking sheet – they do spread quite a lot.)

Baking one tray at a time: bake for 11 – 13 minutes. (I cook mine for 12 minutes.)

Baking two trays at a time: add one minute to the total time to cook. Bake for half this time and then quickly swap the trays over i.e. put the top tray on the lower shelf and the tray from the lower shelf and on the higher shelf and cook for the remaining time.

(So for one tray I cook for 12 minutes and 2 trays for 6½ minutes, swap the trays and then another 6½ minutes = 13 minutes on total.)  

The cookies are cooked when: they have spread out, are starting to brown on the edges and look ever so slightly underdone. They should still be soft in the middle. Let them cool on the baking sheet for 10 minutes and then transfer to a cooling rack.