Place a medium pot over medium-high heat and melt the butter. Add the sage and cook until aromatic and lightly golden, 2-3 minutes. Add the milk and chicken stock to the pot and bring to a boil.
When the liquids boil, whisk in the polenta and cook, continuing to whisk, until thickened, 2-3 minutes. Season the polenta with nutmeg, the grated Parm, salt and pepper.