Ideas on a dessert for my grandparents 40th anniversary party?

My grandma & grandpas 40th anniversary party is this Sunday. They have done so much for me and my entire family. My grandma is the funniest woman I have ever met(: she does whatever she can to make others happy, and satisfied, and always focuses on others rather than herself...and my grandpa is the most dedicated, and respected man I have ever met. He worked for the post office for 38 straight years, NEVER missing a day of work. He retired about 5 years ago, and still volunteers on the Midway Boat Museam almost every day. (I have never seen him upset before, and they both always have a smile on their face) .. I want to have at least a small part in their anniversary party, to show how grateful I am for them both. Any ideas on a dessert or something I can make for them? Or anything to show how much I care about them both?