Potato, onion and herb pie | Women's Weekly Food

Ingredients

• 3 potatoes (600g), peeled
• 50 grams butter
• 1/4 cup (60ml) olive oil
• 1 brown onion (150g), sliced thinly
• 2 tablespoons finely chopped fresh parsley
• 2 teaspoons finely chopped fresh thyme
• 1/2 cup (125ml) milk
• 1/2 cup (125ml) cream
• 2 eggs, beaten lightly, separately
• 1 (sheet) ready-rolled puff pastry pastry
• 1 cup (150g) plain flour
• 90 grams butter, chilled
• 1 egg yolk
• 1 tablespoon lemon juice, approximately