Blue cheese and pear tart

Ingredients

• 1 sheet thawed frozen puff pastry (8.6 oz.)
• 1 large egg
• 2/3 cup Gorgonzola dolce cheese
• 1/2 small onion, sliced
• 1 tablespoon olive oil
• 1 ripe pear, thinly sliced
• 2 tablespoons fresh thyme leaves