Place carrots cut side down in a pan a fry with butter to caramelise. Then spoon onion jam over the top and pastry, tucking the edges in and under.
Bake in oven until pastry is golden and puffed up.
Once cooked and ready to turn out, place a large plate over pan and flip over. Top with crumbled feta and thyme leaves. A drizzle of honey is nice too.