COLUMBIA, S.C. — Highland Baking Co. plans to invest $9.48 million to build a new production facility in Spartanburg County, S.C. The wholesale bread baker is based in Northbrook, Ill., and specializes in producing custom bread products for national restaurant chains. The South Carolina facility, which is expected to open in October, will allow Highland to add capacity and improve efficiencies, the company said. “This is an important step in our company’s growth,” said Stuart Rosen, vice-president of Highland Baking. “Spartanburg County is a great fit for our business and offers a business-friendly climate and excellent market access.”