Melt the butter in large deep skillet. Add the onion and cook over moderate heat, stirring, until translucent, 4 to 5 minutes. Add the whole corn kernels and cook, stirring, until crisp-tender, about 10 minutes. Add the corn puree and cook until slightly thickened, 8 to 10 minutes. Reduce the heat to low, add the cream and salt and cook until heated through. Serve warm.