In a large, heavy-bottomed saucepan, combine the stock with the bay leaf, salt, and pepper.
Bring to a strong simmer over high heat and slowly (carefully because it will spit at you) add the polenta, whisking constantly. Reduce the heat to low, stirring often with a large wooden spoon, until the polenta thickens, about 25 minutes.
Add the butter and Parmesan and stir until melted. Adjust seasoning to taste, garnish with chives, and serve right away.