This is Dr. Christian. Welcome to JustAnswer. A few questions will help me get a clearer picture of the situation:
She weighs 33lbs.
She ate the cupcakes about 3/4's of an hour ago.
She seems fine but I am worried.
Thank you for the information. More than likely she will be just fine. The paper cupcake wrappers should pass fairly easily and the cupcake itself isn't dangerous. You can try getting her to vomit up the cupcake with 4-5 teaspoons of hydrogen peroxide orally. It can be repeated in 10 minutes. After her stomach has settle (an or hour or more) you can give her a regular meal mixed with canned pumpkin. The fiber will help move the paper through. You'd be amazed what will pass through the intestines of a dog. The symptoms of a problem would be vomiting, belly pain, lack of appetite, lethargy and straining to defecate. If that occurs then have her checked immediately. If you have more questions please let me know.