Place the whole cranberries, strawberries, brown sugar, ground cinnamon, ground nutmeg, ground cloves, and ground ginger into the slow cooker. Stir thoroughly to ensure the fruit and spices are evenly distributed.

Cover the slow cooker and cook the mixture on HIGH for 4 hours. Do not open the lid or stir during cooking, as this will allow the flavors to develop and prevent excess moisture from escaping.

Transfer the contents of the slow cooker into a blender. Pulse until you achieve a jam-like consistency, being careful not to over-blend, or it may turn into cranberry butter. Alternatively, use an immersion blender directly in the slow cooker for easier cleanup.

Let the jam cool to room temperature. As it cools, it will thicken considerably thanks to the natural pectin in the cranberries. Once cooled, transfer to jars or an airtight container for storage. I like to sample a little while it’s still slightly warm—it’s delicious on toast or stirred into yogurt!