Don't ask for her to help. Have everything prepared, kept on low in the oven or in the fridge, and have wine ready. The kitchen (and your bathroom, and your bedroom) should be spotless. The table should be set. Share a drink first, provide an appetizer, and then she can wait as you serve dinner. The music can be Jazz, Beatles, or something she likes that's on the quiet side.
You might also try serving her outside on a picnic table.
Use a table cloth, real napkins, candles and fresh flowers along with a wine chiller if white wine is served.
Serving a woman dinner is one of the most important skills a seducer can have, but it takes practice. Done properly, she'll be taking a photo of the table before she sits down. In fact, you should always take a photo of the table before serving her (ideally with her seated). No two dinner tables are ever alike.
She can help clean up afterward if she wants but don't insist.