Heat a Dutch oven or soup pot over medium heat with the oil.
Add the bacon and stir until crispy but not overcooked, 5 minutes or so. Add the onions and garlic, then stir in the thyme and pepper. Cook for 30-35 minutes, stirring occasionally, until the onions are very sweet and caramel in color. Turn the heat up to medium-high, then add the beer and reduce by half. Add the Worcestershire, stock and water to the pot and simmer for the flavors to combine. Season with salt, to taste.
Heat the oven to 350°F.
Brush the bread slices with a little melted butter and bake for 12-15 minutes, until golden and toasted. Top the toast with the blue cheese and return to the oven for 3 minutes to melt the cheese. Remove from the oven and top with the herbs.
Fill the soup bowls and top with blue cheese croutons.