- Ground beef 80/20 – 450 g (1 lb)
- Salt & black pepper – to taste
- Cremini mushrooms – 200 g 7 oz
- Butter – 30 g 2 tbsp
- Whiskey – 60 ml ¼ cup
- Soy sauce – 15 ml 1 tbsp
- Brown sugar – 5 g 1 tsp
- Butter garlic drizzle – 45 g (3 tbsp)
- Garlic – 2 cloves minced
- Pinch of salt
- Fresh parsley – 1 tbsp chopped
- Swiss cheese slices – 4
- Burger buns – 4
Optional toppings: lettuce, caramelized onions, pickles