Cheesy Mushroom Pie - A better choice!

Ingredients

• 500 grams portobello mushrooms, sliced
• 1 onion, finely chopped
• 2 garlic cloves
• 1 egg, whisked
• 1 tablespoon olive oil
• 2 sheets of puff pastry
• 2 teaspoon sesame seeds
• Salt and ground black pepper
• 1 cup grated cheese