Combine butter and onion; let stand a few minutes.
Arrange biscuits on an ungreased baking sheet.
Make a depression in the center of each biscuit with back of spoon or bottom of small glass.
Fill each depression with 1 teaspoon onion-butter mixture.
Bake at 450° for 8 to 10 minutes or until biscuits are done and onion is toasted.