Using a stand mixer with a paddle attachment if you have one, cream the butter and sugar together until pale and fluffy.

Add the egg, lemon zest, baking powder, vanilla/almond extract, and a couple of tablespoons of flour and mix gently to break up the egg.

Tip in the rest of the flour and stir carefully until the ingredients come together to form a soft dough.

Roll the dough into 24 equal balls (they should be roughly the size of a large walnut).

Lay the balls on a tray lined with greaseproof paper and gently make an indentation in the top of each one; although the name suggests pressing your thumb into the cookie, I actually find using a bottle cap or tiny measuring spoon gives a more regular shape!

Add half a teaspoon of raspberry jam into each little hole, then pop the tray in the fridge for at least an hour to chill the cookies.

To bake, preheat your oven to 180 degrees. Arrange the cookies on a baking sheet lined with greaseproof paper (I find six or eight to a sheet works very well as they will spread a little) and then cook in the centre of the oven for 10-12 minutes until golden.

Allow to cool and then dust on a little icing sugar to serve.