In a medium saucepan, melt butter over medium heat. Add shallot, and cook until translucent, stirring occasionally, about 2 minutes. Add sage leaves and juniper berries; cook, stirring, 1 minute. Add cranberries, maple syrup, apple cider, jelly, salt and pepper. Raise heat to medium-high, and simmer until cranberries are soft and starting to burst, about 3 minutes.
Transfer cranberry mixture to a food processor, and puree until smooth. Pass puree through a fine sieve into a small saucepan.
Return glaze to stove, and simmer gently over medium heat until it has thickened, about 10 to 15 minutes; you should have about 1 1/4 cups. If glaze seems too thick, thin it with a little apple cider. Keep warm until ready to use.