Combine flour, sugar, baking powder and salt. In another bowl beat eggs, onion, and butter to blend.
Stir wet into dry ingredients until moistened. Fold in walnuts and cheese.
Fill greased or paper-lined muffin cups three-fourths full. Bake for 10-12 minutes or until done. Cool 5 minutes in pan before turning out to a cooling rack.
Recipe by Jellibean Journals at https://jellibeanjournals.com/sweet-onion-muffins-where-have-you-been-all-my-life/