In a large, heavy saucepan, toast the poppy seeds over high heat, stirring, until they smell slightly nutty, about 2 minutes. Transfer to a small bowl. Add 5 tablespoons of the butter to the saucepan and cook over moderate heat until beginning to brown, about 5 minutes. Stir in the beets and season with salt and pepper. Reduce the heat to low, cover and cook until the beets are tender, about 10 minutes.