Mini pissaladières

Method

1. Melt the butter in a large saucepan, then add the onions. Cook over a low-medium heat for 40-45 minutes, stirring often, until the onions have reduced and look sticky and golden. Spread out on a plate and leave to cool completely.
2. Unroll the pastry on its paper, trim away any uneven edges and cut into 24 squares. Use the tip of a sharp knife to score a thin border around each square, then brush the border with beaten egg. Transfer the squares, spaced out on their paper, to a baking sheet and chill for 20 minutes. Heat the oven to 200ºC/180ºC fan/gas 6.
3. Once the pastry has chilled, bake for 10 minutes until puffed and crisp. Remove from the oven (use a sharp knife to separate any that are stuck together). Press down the middles with the back of a teaspoon, then fill with 1 tsp of the onions. Cross 2 anchovy pieces over each tart, then top with thyme and an olive half.
4. Transfer the tarts to another baking sheet (discard the paper) and bake for 5-10 minutes until the pastry is deep golden and the onions have shrivelled slightly. Serve warm.