Creamy Green Bean Casserole from Scratch Recipe - Recipe Tweets

Ingredients

• 1 medium onion
• 1/2 teaspoon salt
• 1/4 teaspoon ground black pepper
• 1 large egg
• 1 Tablespoon 1 + 1 teaspoon salt, divided
• 1 pound fresh green beans, rinsed, ends trimmed, and halved
• 8 ounces sliced mushrooms*
• 1/2 teaspoon ground black pepper
• 2 cloves garlic, minced
• 1 and 1 1/4 cups