Guinness Turkey Shepherds Pie

Name: Guinness Turkey Shepherds Pie
Ingredients: 1 1/2lb ground turkey; 1 C diced carrots; 1 large onion, chopped; 2 C sliced white mushrooms; 4 C mashed potatoes, seasoned to your liking (I had some Simply Potatoes mashed potatoes that I scored at a BOGO sale which made this recipe super simple to make!); 3/4 C Guinness beer; 1 tbsp olive oil; 1 tbsp Worcestershire sauce; 1 14.5oz can french cut green beans, drained and rinsed; 1 tbsp ketchup; 1/4 C all-purpose flour; Salt to taste; 1 1/2 C shredded cheddar cheese