Melt butter in a skillet. Add shallots and leeks, sauté until translucent. Remove skillet from the stove, carefully set the skillet back, keeping your face away. Add Sambuca and cook for 1 minute.
Add cream and spinach. Cook for 2 minutes, then fold in the garlic. Line oysters on a baking sheet. Spoon sauce on the top and sprinkle with parmesan. Bake for 7 minutes and serve hot.
Makes: 4