Ham and Cheese Puff Pastry Slab Pie

INGREDIENTS

sheets puff pastry (, defrosted and rolled into 10-inch squares)

1 tbsp

Dijon mustard ((Smooth or grainy, your preference))

6 oz

shredded Emmental swiss cheese

4 oz

thinly-sliced ham ((I use Black Forest or Virginia))

1/3 cup

caramelized onions

1 tsp

chopped thyme leaves

large egg

1 tbsp

milk

1/4 tsp

garlic powder

1 tbsp

chopped fresh parsley