1. Preheat the grill to high heat, approximately 450°F to 500°F.
2. While the grill heats, boil beer for 2 minutes and set aside to cool slightly.
3. Mix beef, mustard, parsnip, carrot, onion, thyme, bread crumbs, and salt together in a large bowl.
4. Once combined, add beer and continue mixing together.
5. Once the burger mixture is fully combined, separate the mixture into 4 even sections and then form those into 4 patties.
6. Once patties are formed and the grill is hot, place them on the barbeque for 6 minutes per side, or until cooked through.
7. Once burgers are cooked, turn off the grill and add the grated cheddar cheese evenly to the top of each burger.
8. Once the cheese has melted, remove the cheeseburgers from the grill and serve them on a bun with a little parsley sprinkled on top.
