In a bowl, combine the flour, sugar, baking powder, & salt. In another bowl, whisk the egg, milk & butter; stir into dry ingredients just until moistened. Fold in the chips and nuts.
Fill muffin cups 2/3 full. Bake at 400 for 15-18 minutes or until a toothpick comes out clean. Cool for 5 minutes before removing from pan to cooling rack.
For glaze- In a small microwave-safe bowl, melt chips with cream; stir until smooth. Drizzle over warm muffins.