In a large pot over medium heat, add 2 tablespoons of olive oil. Once heated, stir in 4 cloves of minced garlic and 1 teaspoon of red pepper flakes. Sauté for about 1 minute, or until the garlic is golden brown, being careful not to burn it.
Pour in 1/2 cup of dry white wine, scraping the bottom of the pot to deglaze and release any flavorful bits. Allow it to simmer for 2-3 minutes.
Add the can of crushed tomatoes to the pot. Season with salt and freshly ground black pepper to taste. Stir well to combine all the ingredients.
Bring the sauce to a simmer, then reduce the heat to low. Allow it to cook for about 5-7 minutes to let the flavors meld.
Add the cleaned mussels to the pot, stirring gently to coat them with the sauce. Cover the pot with a lid and cook for about 5-7 minutes, or until the mussels have opened. Discard any mussels that do not open.
Once cooked, sprinkle chopped fresh parsley over the mussels for a burst of freshness. Serve immediately with slices of baguette or crostini for dipping into the sauce.