Heat the oven to 350F or 180C.
Place the squash open side up. Add the butter, thyme, salt, and pepper. Bake for about 45 minutes.
In a pan, sautee the onion on medium heat, stiring frequently in olive oil until golden. Remove from heat and incorporate the sauerkraut, parsley, cheese, cornstarch, and cream.
Carefully remove the hot squashes from the oven. Use some of the butter in the center of the squash to brush the edges of the squash. Divide the miture between the squashes and then return to the oven. Bake 25 minutes or until the center is bubbly and the edges are goden brown.