Tomato Mozzarella Tart

1. Thaw the puff pastry sheet (this typically takes 30-40 minutes) and preheat the oven to 400F.
2. Place the two thawed sheets of puff pastry on a baking sheet, overlapping them slightly in the middle, and crimp the edges so that they stand up slightly and you have a rim around the edges. Sprinkle the breadcrumbs evenly over the pastry.
3. Cut the onion in half lengthwise and slice it into very thin half-moons. Distribute the onion slices evenly over the puff pastry.
4. Tear up the mozzarella and put half of it on top of the layer of onions (we’re saving the other half to top the tart off after it bakes).
5. Cut each tomato into 4 thick slices, and put the slices on top of the onions and cheese in rows, fitting the slices closely together.
6. Sprinkle most of the thyme over the tomatoes (reserving some) along with a generous amount of salt and pepper. Sprinkle a little sugar on top as well, and finish it off with a little olive oil poured across the tart in a very thin stream.
7. Put the tart in the oven and bake for 30-40 minutes, until the edges are puffed up and the tomatoes are roasted.
8. Finish the tart off with the rest of the mozzarella and thyme sprinkled on top.