Heat oil in a large frying pan over medium-high heat. Add onion, garlic and thyme. Cook, stirring, for 4 minutes or until softened. Add zucchini and cook, stirring, for 3 minutes or until softened. Add flour and stir until combined. Transfer to a large bowl. Stir in ham and corn. Season. Set aside to cool slightly.

Grease a 22 x 28cm (base measurement) rectangular baking dish. Use the shortcrust pastry to line the base and sides of the dish. Trim excess pastry.

Place a 28cm-long piece of baking paper on a work surface. Cut the puff pastry into 2.5cm-wide strips. Arrange 8 Pastry Strips across the baking paper. Arrange the remaining pastry strips in the opposite direction (joining strips together to make longer strips, if necessary), layering to create a lattice pattern

Whisk 8 of the eggs and the milk in a large bowl until combined. Season. Transfer the ham mixture to the pastry case. Pour over egg mixture. Sprinkle with the cheese. Brush some of the extra egg around the edge of the pastry. Top with the latticed pastry strips. Trim excess. Brush with a little more egg.