Combine 1 1/2 cups flour, onions, baking powder and salt. With pastry blender or fork, cut in shortening until mixture resembles fine crumbs. Stir in milk just until moistened. Stir in peas. Drop dough by rounded tablespoonfuls onto chicken mixture. Cover; cook on high setting 45 to 50 minutes or until toothpick inserted in center of topping comes out clean.