Tatin Tart with Caramelized Onions, Gorgonzola and Mustard

Directions

1. Pre-heat oven to 350, rack in the middle.
2. Trim, wash and slice vertically the spring onions.
3. Melt the butter and add the onions with 2 tbsp of the sugar. Add salt and pepper and stir. Cook the onions until golden brown.
4. Butter a 9 inch round non-stick cake pan. * Sprinkle with the remaining 2 tbsp of sugar, a little salt and freshly ground pepper. Put the onions in a tight layer, lengthwise. Remember this will be the top of the tart so the nicer you make it look, the prettier the tart will be when inverted.
5. Divide the cheese over the onions.
6. Open up the puff pastry disk and smear with the Dijon mustard leaving a border with no mustard. Cover the onions and cheese with the pastry, mustard side down. Roll and tuck in the pastry around the pan to make the rim thicker than the bottom.
7. Prick the dough with a knife to make some ventilation holes and bake in the oven for 20 to 25mn until pastry is golden brown and puffy.
8. Allow the Tatin Tart to cool for 10 minutes then invert on a serving plate.
9. * If you don't have a non stick pan follow this method: cut a 9 inch circle of parchment paper. Butter the bottom of the pan, adhere the parchment paper and butter the parchment paper. Follow the rest of the method as above.
10. If you want to serve the tart later, refrigerate before baking.