Sweet Potato Turkey Burgers

Ingredients: 

• 1.25
  Lean ground turkey (or extra lean ground beef) 
• 1
  Small sweet potato 
• 1/2 cup
  Chopped frozen spinach (thawed and squeezed dry or 1 cup fresh) 
• 1 tsp
  Salt 
• 1/4 tsp
  Pepper 
• 1/2 tsp
  Garlic powder 
• 1/2 tsp
  Onion powder 
• Whole grain buns (or lettuce wraps) for serving (optional)