Start by mixing the butter and icing sugar together until well combined and creamy looking. This is best done in a stand mixer with the paddle attachment for 3-5 minutes.

Add the egg yolk, vanilla extract and milk, and mix until fully incorporated.

Add the plain flour and salt, and mix until combined.

Bring the mixture together into a dough and form a rough disc shape. Wrap the dough in cling film and put it in the fridge to chill for 30 minutes.

Meanwhile, pre-heat your oven to 160C Fan/350F/Gas Mark 4, and line a few baking trays with baking paper.

Using a rolling pin, roll the dough out onto a floured surface to a thickness of 3mm. Keep turning the dough as you roll, to ensure it doesn't stick to the surface, and add more flour underneath as needed.

Cut out your biscuit rounds and place them onto the lined baking trays, then cut heart shapes out of half of them. You will need to re-roll out the dough to use it all up.

Bake the biscuits for 10 minutes, or until lightly golden, then leave to cool on the trays for at least 10 minutes before moving to cooling racks.

When they are full cool, spread some seedless raspberry jam over one of the biscuit rounds, about 1 tsp per biscuit, then top with a biscuit round that has had a heart cut out of it. Repeat until all of the biscuits have been sandwiched together.

Store in an airtight container in a cool place for 3-4 days, you can also freeze them.