Preheat your oven to 180°C/350℉ (160°C/325℉ for fan and convection ovens). Then line a large tray or two with baking paper.
Add the softened butter to a bowl with the brown sugar and treacle. Mix well then stir in the egg and vanilla extract until smooth.
Add the flour, ginger, cinnamon, nutmeg and salt. Mix well and when it starts to come together, use your hands to press it into a ball of dough.
Divide the dough into 12 equal-sized pieces and divide each piece into 2.
Roll one piece into a ball and press into the middle of it with your thumb to create a dent. Fill it with 1 teaspoon of caramel. Create a flat disc with the other piece and use it to cover the caramel, then gently press the edges of the two pieces together. Repeat for all 12 cookies.
Place the cookies onto your lined tray and bake for 10-12 minutes until golden brown at the edges.
Let them cool completely before removing them from the tray then enjoy.