Low-Sugar Baked Nectarine Jam Recipe

Cut fruit from pits and coarsely chop. In a 10- by 15-inch baking pan, mix fruit, sugar to taste, and lemon juice.
Bake, uncovered, in a 375 degrees F oven until juices are released, about 10 minutes. Meanwhile, put a small ceramic plate in the freezer.
Reduce oven temperature to 325 degrees F. Every 20 minutes or so, gently stir fruit to moisten well with juices. Bake fruit until a little of its liquid, spooned onto the chilled saucer, doesn't immediately flow together when you pull the tip of a spoon or your finger through it (as you lift the spoon or your finger, the liquid holds on, forming a small droplet), 45 to 55 minutes.
Let jam cool. Or, if necessary, adjust consistency: If too runny, return to oven, then stir and test every 20 minutes until jam reaches desired thickness; if too thick, warm it in the oven, then stir in water, 1 teaspoon at a time, until it is the desired consistency. Spoon into a serving bowl or small jars. Serve, or cover airtight and chill up to 2 weeks; freeze to store longer.