Add the softened butter and sugar to a large mixing bowl. Using an electric handheld mixer, beat the mixture for 2-3 minutes until it's light and fluffy.

Add the egg, vanilla and sourdough discard and beat just enough to combine, scraping the sides of the bowl if needed.

In a separate bowl, mix the flour, baking soda and salt.

Add the flour mixture to the butter mixture and fold and knead just enough to incorporate – you do not want to overknead as it will lead to tough cookies.

Line a large baking sheet with parchment paper.

Scoop small spoonfuls of dough (18-20g per cookie) and shape them into balls with the palms of your hands. Arrange them on the prepared baking sheet, leaving about 4cm (2in) in between.

With your thumb, the back of a small spoon or the end of a thick wooden handle, press the centres of each cookie down to create a well. It helps if you oil the tool you're using in order for it not to stick to the cookie dough.

Place the tray in the fridge for 30 minutes.

Preheat the oven to 190°C (375°F).

Add a teaspoon of jam to each well (do not overfill as the jam may overflow when baking).

Place the cookies in the preheated oven for 10-12 minutes, or until starting to turn golden brown around the edges.

Leave the cookies on the tray for 5-10 minutes, then transfer them onto a wire rack to cool down completely.