Classic Green Bean Casserole - Better Than Bouillon

Ingredients

• 1.5 pounds fresh green beans, trimmed and cut in half
• 4 tbsp unsalted butter, divided
• 8 ounce slices brown mushrooms
• 2 tbsp finely chopped fresh thyme
• 2 cloves garlic, minced
• .25 cup all-purpose flour
• 1 teaspoon cracked black pepper
• 2.5 cups whole milk
• 2 tbsp Better Than Bouillon Seasoned Vegetable Base
• 2 tbsp Dijon mustard
• .50 cup Parmesan cheese
• 1 cup store-bought crispy fried onions