Heat olive oil in a medium saucepan over medium heat. Stir in shallots and garlic, and cook until tender. Stir in fennel and tomato, and continue cooking about 5 minutes.
Mix white wine, ouzo, and heavy cream into the saucepan, and bring to a boil. Gradually stir in mussels, 1/2 the basil, and salt.
Cover saucepan, and continue cooking about 5 minutes, until the mussels have opened. Garnish with remaining basil to serve.