Gluten Free Shepherd's Pie - The Measured Scoop

Ingredients

• 2 lb yellow potatoes
• 1/3 cup milk
• 3 tablespoons unsalted butter
• 3 teaspoons salt, divided
• Black pepper
• 1 tablespoon unsalted butter
• 1 tablespoon olive oil
• 1 cup diced onion, about 1/2 large onion
• 1/2 cup diced carrot
• 1/2 cup diced celery
• 2 teaspoons minced garlic
• 1 lb ground beef
• 1 1/2 teaspoons salt
• 3/4 teaspoon black pepper, divided
• 2 cups beef broth
• 2 teaspoons Worcestershire sauce
• 1 tablespoon tomato paste
• 1/2 cup green peas (optional)
• 4 tablespoons cornstarch
• 1/4 cup water water