Gluten-Free Shepherd's Pie

Ingredients

• 2
  slices bacon (preferably nitrate-free)
• 1
  pound ground beef (OR ground lamb)
• ½
  cup onion (chopped)
• 1
  stalk celery (chopped)
• 1
  carrot (chopped)
• 1
  cup mushrooms (chopped)
• 1
  cup peas (frozen)
• 2
  tablespoons sweet rice flour
• 1
  tablespoon tomato paste
• 1
  tablespoon gluten-free Worcestershire
• ½
  to 3/4 cup beef stock
• 2
  teaspoons thyme (fresh)
• 1
  tablespoon parsley (fresh, chopped)
• Optional: 1 teaspoon rosemary (fresh, minced)
• 1 ¾
  pounds potatoes (red or Yukon Gold)
• 2
  tablespoons butter
• ¼
  cup milk
• 3
  ounces cheddar cheese (shredded)
• 1
  tablespoon chives (fresh, chopped)
• Salt and pepper to taste