In a large bowl, combine the cold water and flour. Stir until flour is incorporated. Add the mussels and allow to rest for 30 minutes to help release the sand from the shells. Drain, remove the beards from the shells, and discard any shells that are not firmly closed. Set usable mussels aside.

In a large pot, melt the butter with olive oil over medium-high heat. Add the garlic and brown for approximately 1 minute. Add chopped bacon and cook until crisp, approximately 5 minutes. Drain approximately half of the bacon fat out of the pan (this will help prevent the broth from being too greasy).

Add the thyme, wine, salt, pepper, and red pepper flakes to the pot. Bring the mixture to a boil, then reduce to a simmer over medium heat. Add the mussels to the broth, cover the pot, and cook for approximately 8 to 10 minutes. Remove from heat and discard any shells that have not opened.

Sprinkle the Gorgonzola over the mussels and serve immediately with bread.