In your crockpot, combine the cranberries and strawberries, ensuring all pieces are evenly distributed. Sprinkle granulated sugar, light brown sugar, and the holiday spices over the fruit. Stir gently to coat the berries well.

Cover the crockpot and set it to cook on high for 4 hours. Stir halfway through to prevent sticking. The cranberries will burst, forming a luscious jam.

Once the cooking time is up, blend the hot fruit mixture in the crockpot for 2-3 quick pulses using an immersion blender, or skip for a chunkier jam.

Ladle the warm jam into clean, pre-warmed jars, ensuring to wipe the rims for a proper seal. Secure the lids lightly.

Let the jars cool at room temperature for about an hour. Transfer them to the refrigerator for optimal setting, ideally overnight.