Add the butter to a saucepan over medium heat and let it melt, stirring occasionally.

Continue cooking for 5–7 minutes until the butter turns golden brown and smells nutty, with little brown flecks at the bottom.

Pour into a mixing bowl and leave to cool slightly.

Add the brown sugar, egg and vanilla extract to the browned butter and whisk until smooth and combined.

Add the flour, salt and baking soda, mixing until a cookie dough forms.

Fold in the milk and dark chocolate chunks until evenly distributed.

Line a baking tray with parchment paper.

Place four digestive biscuits on the tray, leaving plenty of space between them so the cookies have room to spread.

Place two mini marshmallows or one large marshmallow in the centre of each digestive biscuit.

Divide the cookie dough into four equal portions and roll each portion into a ball.

Using the palms of your hands, flatten each dough ball into a thick disc.

Place one disc over each marshmallow-topped digestive biscuit, gently spreading the dough over the top and sides to cover both the biscuit and marshmallow.

Gently cut a little of the dough to expose part of the marshmallow, allowing it to peek through the top of each cookie.

Once all four cookies are assembled, place the baking tray in the fridge for 30 minutes. This helps the cookie dough firm up so the cookies hold their shape while baking.

Preheat your oven to 180°C conventional or 160°C fan.

Bake for 16–18 minutes, or until the edges are golden and the centres are still slightly soft.

The marshmallow should peek through the top of each cookie, giving them their signature s’mores look.

Leave the cookies on the baking tray for around 10 minutes to firm up before transferring them to a wire rack.

Finish with a little flaky sea salt, if desired, and serve while the chocolate and marshmallow are still gooey.