Add cranberries, pear, ginger, rosemary leaves, maple syrup, and water to a medium saucepan. Cook over medium-high heat, stirring occasionally, until the mixture starts to boil and the cranberries burst open, approximately 5 minutes.
Reduce heat to medium-low and simmer for another 5-10 minutes. While cooking, mash the cranberries and pears with a wooden spoon. Season with a pinch of sea salt and stir to combine.
Remove from heat and allow sauce to cool for 15-20 minutes before checking the consistency. Add a little water if the sauce is too thick. Taste and add more maple syrup for a sweeter sauce, if desired.
Optional: For a smoother sauce, blend one-half of the cranberry mixture in a food processor or blender until smooth. Stir puree back into the remaining saucebefore serving.