Marinating the peaches

Slice the peaches into 1/4-inch (0.5 cm) thick wedges.

Mix the sugar with the lime juice and zest, and the rosemary sprigs.

Add the peach slices, toss to coat, then cover with plastic wrap.

Refrigerate for 40 minutes to 1 hour.

Drain the peaches, reserving the juice (you'll use it later). Also keep the rosemary sprigs.

Assembling the tart

Place the puff pastry sheet on a baking sheet. Arrange the peaches on top, leaving a border around the edges.

Brush the peaches with melted butter, then fold the pastry edges over the peaches.

Brush the pastry border with the beaten egg.

Bake for 20 minutes in a preheated oven at 350°F (180°C).

Peach syrup

While the tart bakes, heat the reserved peach syrup with the cornstarch for about 2 minutes, until it thickens and coats a spoon.

After 20 minutes, remove the tart from the oven, brush it with the peach syrup, and sprinkle with the rosemary leaves (from the marinade).

Return to the oven and bake for another 15 to 30 minutes, until the tart is golden brown.

Let cool on a wire rack before serving.

💡 It's best not to make this tart the day before, as the pastry can get soggy from the peaches.