Cheesy dip with beer caramelized onions - Le Coup de Grâce

Ingredients

• 2 big vidalia onions, cut in half then finely sliced
• 1/4 cup butter
• Olive oil
• 175g pancetta, cut in small cubes
• 1/4 cup Don de Dieu beer by Unibroue
• 1 tablespoon fresh thyme
• 2 cups Gruyère cheese, grated
• 2 cups cheddar cheese, grated
• 1/2 cup 5% sour cream
• 1/2 cup light cream cheese
• 1 scallion, finely sliced
• Salt and ground pepper