1. Add the butter and sugar to a large bowl and mix for about 3-4 minutes until very light and fluffy. Add the egg and vanilla extract and mix in well. In a separate bowl mix the flour with baking soda and salt – add to the bowl, and mix until just combined. Next, add the chopped chocolate and fold in. Cover the bowl and place in the fridge for about 2 hours (or overnight).

2. Preheat the oven to 350°F (180°C). Grease several mini muffin trays and add about 1 tablespoon of the cookie dough to each well. Bake the cookie cups for about 12-13 minutes – they should be firm around the edges but still soft in the centers. Remove from the oven and let cool for about 2 minutes, then press the Toffifay (Toffifee) into the still-soft dough. Leave the cookie cups to cool completely in the muffin trays. Remove the cooled cookie cups from the molds using a sharp knife. The cookie cups should be eaten within 4-5 days.