1. Preheat the oven to 200C/Gas 6.
2. To make the tart, put the shallots in a small pan and cover with water. Bring to the boil and simmer for 2-3 minutes, until they start to soften, but are still firm. Drain and refresh under cold running water and cut in half. Drain on kitchen towel.
3. Heat the butter in a 12-14cm ovenproof tart tatin pan over a medium heat. Add the sugar and stir over a low heat until dissolved. Simmer for a minute or two, then add the shallots and season with salt and pepper. Remove from the heat and set aside.
4. Roll the pastry out to a circle 3cm large than the pan. Lay the pastry over the shallots, tucking the edges into the pan. Bake in the oven for 15 minutes, until the pastry is risen and golden. Remove from the oven and set aside for 2-3 minutes.
5. Turn the tart out on to a baking sheet and place the goats cheese on top. Brush with the egg and return to the oven for a further 2 minutes. Keep warm whilst you make the sauce.
6. To make the sauce, melt a little of the butter in a small saucepan and add the shallots. Cook for 2-3 minutes, until softened.
7. Add the vinegar and wine and simmer until reduced by two thirds. Add the cream and bring to the boil. Reduce the heat and whisk in the cold butter. Do not allow the sauce to boil.
8. Add a drop of lemon juice a pinch of cayenne pepper and season with salt and pepper. Stir in the chives. Serve the tart with a little of the sauce.