French Onion Baked Brie - Better Than Bouillon

Ingredients

• 2 Tbsp butter
• 3 large onions, thinly sliced
• 1 Tbsp finely chopped fresh thyme
• 1/4 tsp pepper
• 2 Tbsp Better Than Bouillon Roasted Beef Base
• 1 egg
• 1 Tbsp milk
• 1 sheet frozen puff pastry (10-inch square), thawed
• 1 round (8 oz) Brie cheese, very cold
• 1 pkg (8 oz) crackers