Melt the butter in a pan with the bouillion powder and 2tbsp water over a gentle heat. Add the sliced leeks, thyme leaves and season. Cover with a lid and allow to soften for 10-15 mins.
Heat the oven to 200C/gas mark 6. Cut out 6 x 10cm circles from the pastry, using an 8cm cutter make an indentation in each to create a border. Score the base of the pastry to prevent it rising too much, then brush the borders with a little milk. Bake for 10-12 mins, until golden and risen.
Turn the oven off. Push the scored centres of the pastry down and spread each with 1tbsp tapenade. Top with leek. Return to the oven to reheat just before serving.
Poach the eggs and place on top of the leeks to serve.
Notes
Poach the eggs ahead and pop each one into a bowl of cold water, then gently re-warm in a pan of hot water to serve.