"Based on a recipe from the Raglan Road Irish Tavern in downtown Disney, this is the most amazing soup you'll ever make. Your new 'go-to' for company! You might as well make 2 batches because you'll want leftovers."
Combine vegetable stock and lager in a stock pot; season with salt and black pepper; bring to a simmer over medium-low heat. Cook potatoes in the simmering stock mixture until tender, 20 to 30 minutes.
Stir cream, leek, garlic, and thyme into the stock mixture; bring to a boil, return heat to medium-low, and cook at a simmer another 10 minutes.
Sprinkle cayenne pepper into the soup. Melt cheese into the soup 1 cup at a time while blending with an immersion blender until smooth.