Pour apple cider into a crock pot.

Stir in brown sugar until dissolved.

Place allspice, cloves, cinnamon, and nutmeg into a coffee filter or cheesecloth.

Fold up the filter or cheesecloth securely.

Tie with butcher's twine to create a spice bag.

Place the spice bag into the cider.

Slice an orange in half.

Place the orange halves, cut-side down, into the cider.

Cover the crock pot.

Heat on low for several hours (e.g., 3 hours) before serving, or on high for 1-2 hours, then reduce to low.

Keep the spice bag and orange halves in the cider while heating and serving.

Serve warm.