My nanna used to make biscuits like this all the time.. I recommend you make them as well. Printable Here
You Will Need..

Line a baking tray with baking paper and pre heat your oven to 160 degrees celsius.
In your mixer, put the egg yolk, butter, sugar and vanilla essence.
Mix together until creamy.
Add the flour and mix together to form a dough.
Roll into balls and place onto your prelined baking tray.
Slightly flatten each ball. It’s ok if they’re not perfect. I think it adds a bit of rustic charm!
Gently place your heart cutter into the centre of the cookie and press down without going all the way to the bottom.
Use a spoon to scoop out the middles leaving some dough behind, creating a heart hole well in the middle of the biscuit.
Spoon a teaspoon of jam into each heart. You can use any flavour jam you want, I’m just a bit of a jam snob and will only eat strawberry. Plus, it looks nice as a red heart.
Place in the oven for roughly 10-15 minutes until slightly golden. It’s ok if some of the jam leaks, you can just peel it off the sides when it has cooled down.
Leave to cool and firm on the tray.