Homemade Condensed Cream of Mushroom Soup

Bahan-bahan (4 porsi)

• 1 (12 ounce each) can evaporated milk (you can use regular milk in a pinch, it just won't be quite as creamy)
• ½ cup chicken broth
• 1 ½ teaspoons onion powder
• 4 tablespoons cornstarch
• 1 tablespoon olive oil
• ¼ teaspoon black pepper
• 1 cup mushrooms