"child-sized" portion of dessert and mall fun

Note, I will be out of town and not posting for the week of Jan 20- Jan 29th...We went to Rosedale mall recently. A few thoughts...One of our favorite things at the Rosedale mall is looking for fossils in the stone flooring. There are these amazing Amenids all over the floor and we have a great time walking around looking for them. Look for fossils when you are out places, the Minneapolis Art Museum has some fossils too...Then we ate at Ruby Tuesdays which I like generally. (Here is an eating-out post from awhile ago  and a video I did about eating out.) M enjoyed the salad bar and pasta with red sauce. I asked for an ice-cream for dessert (from the children's menu) and showed them an appropriate size for an ice-cream dessert. I asked for one ball, I usually show them a size with my hand. Here is what came out. Two large scoops with whipped cream. Not really a "child-sized" portion. M ate more than half, which was fine on that occasion, but shows how tricky it can be when you eat out.I also order the dessert with the meal, but that is usually met with weird looks, or they just don't do it, so I just remind M that dessert will be coming later so she can save room. She has been really upset in the past when she is full and then dessert shows up. She won't eat it, which amazes me that she has the self-regulation thing down, but she is sad...How do you order desserts when you eat out?