Combine kanten flakes, cinnamon, and water in a medium saucepan, and allow kanten to soften. Add ginger slices and bring almost to a boil, stirring occasionally until kanten dissolves. Reduce heat to low, add cider and syrup, and simmer until heated through.
Remove pan from heat and stir in lemon juice, walnuts, raisins, and lemon zest. Set aside.
Preheat oven to 350°. Halve and core pears and arrange halves peel side up in a single layer in an oiled glass baking dish. Push a few cloves into each half and then pour cider aspic to cover. Bake for 45 minutes, basting once or twice.
Let cool, cover, and refrigerate to set before serving.