Marie-Eve's Turkey Pot Pie

INGREDIENTS

• 1 teaspoon olive oil
• 1/2 cup chopped onion
• 1 clove garlic, minced, or to taste
• 1 1/4 cups water
• 1 (10.75 ounce) can condensed cream of mushroom soup
• 2 tablespoons chicken bouillon granules
• 2 potatoes, peeled and cubed
• 1/2 cup chopped celery
• 1 cup peeled chopped carrot
• 1/2 cup frozen green peas, thawed
• 1 1/2 cups cubed cooked turkey
•  
• 2 cups all-purpose flour
• 1 tablespoon baking powder
• 1 teaspoon salt
• 1/4 teaspoon dried basil (optional)
• 1/4 teaspoon dried oregano (optional)
• 1/2 cup cold butter
• 3/4 cup milk, or as needed
• 1 egg