Step 1In a wide pot or Dutch oven, heat the olive oil over medium-high heat until hot. Add the garlic and leek and sauté until aromatic. Stir in the mussels, tossing quickly with the hot oil.
Step 2Add the sambuca, scraping any flavoring from the base of the pot, then stir in the fennel, clam juice and cream.
Step 3Cover and steam the mussels until they open, 3 to 4 minutes. Stir in the chile flakes, and season with salt and pepper to taste. Remove from heat and serve immediately.