sweet potato shephard's pie

Ingredients For sweet potato shephard's pie

• 2 1/2 lb

  sweet potatoes,peeled & diced into 1/2-inch pieces
• 1/4 c

  1% milk
• 3 Tbsp

  unsalted butter
• 1 tsp

  salt
• 1/2 tsp

  pepper
• 1 1/2 lb

  lean ground beef
• 2 md

  carrots,finely diced
• 2

  ribs celery,finely diced
• 1 sm

  onion,finely diced
• 2 Tbsp

  all-purpose flour
• 2 Tbsp

  tomato paste
• 2 c

  reduced- sodium beef broth
• 1

  (10oz.)package frozen peas
• 1 Tbsp

  chopped fresh thyme
• 1 Tbsp

  chopped fresh rosemary