Cut kernels from corn. Purée 1 cup corn kernels and milk in a blender container. In a medium skillet over medium heat, melt butter. Add onion and remaining corn kernels. Cook until onion begins to soften, about 6 – 7 minutes. Add corn mixture from blender container to skillet. Reduce heat to simmer and cook, stirring occasionally for 5 – 6 minutes or until tender. Add cornstarch, thyme, salt, and pepper. Stir well. Simmer, stirring frequently, until thickened, for approximately 6– 7 minutes.