Creamy Curried Cauliflower and Gruyère Gratin

Ingredients (15)

• 4 tbsp unsalted butter
• 1 medium onion
• 1 tbsp curry powder
• 2 1/2 tsp Kosher salt
• 1 tsp white pepper
• 1 tsp garam masala*
• 3 tbsp all-purpose flour
• 3 cups whole milk
• 2 cups heavy cream
• 1 tbsp fresh thyme
• 12 cups cauliflower
• 1 tbsp plus 1 teaspoon fresh lemon juice
• 2 cups Gruyère cheese
• 2 cups panko
• *Available in specialty markets