Maple Onion Jam

My own spin on a recipe (Cooking Light, last December I think; find the original here), that starts with 5 pounds of onions. A bit more than I wanted in jam form! This is close...

Ingredients
2 lbs yellow onions
4 T brown sugar
¼ tsp minced garlic
½ tsp salt
¼ tsp cinnamon
¼ tsp cardamom
pinch pepper
1½ tsp maple syrup
¾ tsp apple cider vinegar

Directions
Rough chop onions into large pieces. In a crock pot, stir together onion, brown sugar, garlic, salt, cinnamon, cardamom and pepper. Cover and cook on HIGH until onions are very soft and mixture is soupy (8 hours or more).

Remove lid; continue to cook until most of the liquid has evaporated (approx 1½ hrs)*. Turn off crock pot; stirr in syrup and vinegar. Cool 30 minutes.

Transfer mixture to food processor. Pulse until chunky but spreadable (or desired consistency). Divide into canning jars or airtight containers. Store in refrigerator.

* If mixture is still very soupy, pour off liquid into small saucepan; add syrup. Cook over high heat until reduced and thickened to a very thick syrup. Return to onions; stir in vinegar and cool completely.