Asparagus tarts with goat cheese

Ingredients

• 2 sheets frozen puff pastry, thawed, halved
• 1/4 cup olive oil
• 1 onion, thinly sliced
• 2 tomatoes, chopped
• 1/2 cup basil leaves
• 2 bunches asparagus, trimmed
• 1/2 cup prepared basil pesto
• 4 slices prosciutto, grilled, torn
• 60 gram goat cheese, crumbled
• balsamic glaze, to serve