1. To make the frosting whisk softened butter and Brie into a uniform mass. Add the pesto and chili sauce and stir well together. Let it set in the fridge.
2. Chop the onions and leeks.
3. Cook the onions slowly in butter in a frying pan over medium heat. When they start getting a little colour, add the sugar to kick start the caramelization. The onions are done when they have turned completely golden brown.
4. Remove the onions from the pan and fry the leeks briefly. Let both cool.
5. Preheat oven to 180°C/350°F (hot air)
6. Beat the butter thoroughly until completely soft. Add sugar and whisk until fluffy. Whip in the eggs one at a time
7. In another bowl mix flour, baking powder, cayenne pepper and thyme. Whisk the dry and wet ingredients together and then carefully add the grated cheddar in the dough.
8. Fill each mold with about 1 tablespoon dough, so the bottom is covered. Add the onion and leek in the middle and add another layer of dough.
9. Bake for about 25-30min until golden and crisp. Let them cool before you decorate with the cheese frosting and a bit of fresh thyme.