Grease a 20cm/8in x 20cm/8in square of aluminium foil or baking parchment. Place the Brie into the middle of the foil or parchment, add the thyme, pear and a little olive oil and season with salt and freshly ground black pepper.
Seal the foil or parchment at the edges to make a bag enclosing the ingredients. Place onto a baking sheet, transfer to the oven and bake for 6-7 minutes.
For the spicy pear and chilli dressing, melt the butter in a small saucepan, add the chopped pear and cook for 2-3 minutes. Add the sugar, vinegar, chilli flakes and olive oil and cook for a further 1-2 minutes.
To serve, place the Brie parcel onto a serving plate, open it and pour over the dressing. Serve with bread to dip into the hot cheese.