Dear Trish,
Macaroni is a type of dried pasta that comes in various sizes but there is no such thing as a macaroni made and labelled as "pudding macaroni".
I presume your confusion comes from the fact we buy "pudding rice to make rice pudding". To make a sweet macaroni pudding just choose a small size and then proceed in a similar fashion to making rice pudding using whole milk,vanilla bean, cream butter and sugar. Cook it slowly in a double boiler and stir it from time to time. You might find it helpful to par cook the pasta for a few minutes in boiling slightly sweetened water, then drain and add the other ingredients. Remember to cook the macaroni pudding until the pasta is tender, as it thickens you may need to add a splash more milk or cream.
Just like rice pudding some people prefer it cooked on the stove and some people liked it finished by baking it in a casserole dish in the oven to form a skin. You might try topping the macaroni pudding with the same sorts of toppings put on rice pudding, fruits, homemade jams, a real chocolate sauce.
Writing this has gotten my creative juices going so I'm off to do some experimenting of my own.
Hope this has helped
Kevin Ashton
Chef and Food Writer
www.wannabetvchef.blog.co.uk