Preheat oven to 400 degrees F. Line a baking sheet with
Place one piece of puff pastry onto the baking sheet and
spread with mustard, leaving a 1/2-inch border.
Sprinkle half of the shredded cheese over the mustard.
Layer ham slices over the cheese, followed by the caramelized onions, thyme,
and remaining cheese.
In a small bowl, whisk together egg, milk, garlic powder,
Lightly brush the border of the puff pastry with the egg
wash. Place the second square of puff pastry over the top and press the edges
Brush a 1/2-inch border on the top sheet of puff pastry
with egg wash. Fold bottom edge of puff pastry over to create a crust of double
thickness. Crimp edges with a fork.
Brush top of puff pastry with egg mixture (you won't use
the entire amount). Cut three, 1- to 2-inch slits in the centre of the pie to
allow steam to escape while baking.
Bake for 25 minutes, until puffed and golden. Let stand
for 10 minutes before slicing into squares or strips and serving.
Substitute Cheddar or Jack cheeses for the Emmental. Or
use a mix!
Substitute Honey Mustard for the Dijon
Instead of ham, try thinly-sliced roast beef with
cream-style horseradish instead of mustard.