Classic Pissaladière

Ingredients

• 2 cups plain flour plus extra to dust
• 1 tsp baking powder
• 1 tsp salt
• 1/3 cup extra-virgin olive oil
• 2/3 cup water
• 5 medium-large brown or white onions halved and very thinly sliced
• 1/2 cup water
• 3 tbsp extra-virgin olive oil or butter
• 1 tsp finely chopped rosemary
• 2 tsp fresh thyme leaves or 1 tsp dried thyme
• freshly ground black pepper
• 14–16 anchovies drained and halved lengthwise
• about 20 kalamata olives
• 1 egg whisked with 2 tbsp water or milk to make an egg wash
• fresh thyme sprigs, to serve