A taste of Disneyland in an African city.

WALT would be proud: The ice- cream parlor, fashioned a la Disneyland, sits lip-smack in the middle of Dar es Salaam, Tanzania. It is called Sno-Creme, and its proprietor is an Englishman named Paul Mullen. To find such a Peter Pan of a man in this remote corner of the world is curious enough. But to find his scoop of private enterprise irrepressibly carrying on business in the middle of socialist Tanzania - that's genuinely surprising.

Mr. Mullen started Sno-Creme a month before Tanzania gained its independence 13 years ago. Given the timing, he might have foreseen that the business would fall subject to changing rules. But Mr. Mullen, a lover of ice cream, fantasy, and Africa, plunged ahead. By 1967, the year countless businesses were nationalized along with the buildings that housed them, he had three shops. Through nationalization, he eventually lost two of them.

Mr. Mullen, who looks on the bright side as naturally as ice cream melts, saw the loss not as a defeat but as a change of course. ''The greatest reason for our work is personal pleasure and making others happy,'' he says. He calls himself ''the boy who never grew up,'' which may account for his undaunted eagerness when restrictions tighten, profits get pruned by government, and supplies grow harder to come by in Tanzania's virtually closed economy.

It is an eagerness shared by his wife, Sharon. ''In some ways,'' she says brightly, recalling the period of nationalization, ''it was a relief to be cut back at that time, because we were running in circles between the three shops and I was pregnant and so was our manageress.''

Trying to run a business in Tanzania today is not for the rigid or the resentful. Over the past decade, the once elegant Dar es Salaam has lost its luster, luxury, and capitalist cash flow. Roads and buildings are crumbling and dusty. Abandoned construction projects stand decaying like huge dinosaur skeletons. Even the famed bougainvillea look limp. Countless private and semiprivate business people have closed up shop. But Mr. Mullen is a rare entrepreneur, who apparently accepts that things don't go smoothly for anyone in Tanzania nowadays because the country is battling against enormous odds to chart its own economic course in a contrary world economic order.what is meant by contrary?

All of which makes one yearn for an ice-cream break. So who slurps at Sno-Creme? Who writes in the guest book that sits on the 10-stool counter next to the plastic Tiki Juice Bar? The book boasts signatures of contented customers from all ends of the earth. But, says Mr. Mullen, ''local Africans are our major customers'' - including President (Julius) Nyerere's wife and children, Mrs. Mullen pipes in. ''They have been here many times.''

''Yes,'' nods Mr. Mullen, pleased with the endorsement. ''And then we've got tourists, Asians, and foreign diplomats.'' One of the key things that keeps them in business, they say, is the enthusiasm of their clients. ''At various times we've considered packing up, but people say things like 'Please don't go till my contract is up!' So we keep staying.''

Mr. Mullen came to Tanzania as a boy in 1948, when the country was still under British administration and Europeans were paying locals 50 cents for a rickshaw ride from the suburbs into town. His father was one of scores of Englishmen working for the then Tanganyika Railroad. Mrs. Mullen's father was another railroad man. She arrived here with him and the rest of her family in 1960. The following year Mr. Mullen started his first ice-cream shop and on opening day met the future Mrs. Sno-Creme.

''The day Paul's shop opened, he gave away free ice-cream cones,'' Mrs. Mullen says with a grin. ''I spent the whole day in line. Time and time again.'' How could Mr. Mullen resist such a fan?

After their marriage, Mrs. Mullen eagerly joined the enterprise.

''As long as I can remember we've had what we call a theme parlor,'' she says. ''The themes used to change regularly. For the Mexican theme we served Mexican ice-cream dishes. Paul grew a beard for the festivities and designed Mexican decorations to match.''

Then there was the western motif. Mr. Mullen donned cowboy boots and spurs, piped in music from western films, and served Wyatt Burp sundaes.

Six years ago the ice-cream man hit upon what he sees as the theme de la theme - Disneyland - and hasn't changed it since. ''That one stuck,'' he explains, ''because I'm a natural Peter Pan. The first Disney film I ever saw was 'Snow White' back in England in 1938 when I was knee-high to a grasshopper. I never forgot it.''

Apparently not. Today he is clad head to toe in white, an ice-cream cone scarf ring at his neck, a Walt Disney bar pin on his breast pocket. His shop's interior is a takeoff on Main Street of Disneyland, inspired by a pilgrimage he and Sharon made there in 1976 along with their pretty, freckle-faced daughters, Michelle and Carol.

''That trip was Paul's dream come true,'' Mrs. Mullen says. ''He kept buying bendy toys of Mickey and Donald - for himself - until he had a suitcase full. It was very embarrassing,'' she says with a laugh. When they returned to Tanzania, Mr. Mullen got busy redesigning the parlor. He constructed a 4-by-10-foot replica of Sleeping Beauty's castle and crafted bas-reliefs of Disney characters: Pluto guffawing, Mickey waving a white-gloved hand, Donald tipping his sailor's cap.

In 1979, he opened a workshop that is the equatorial answer to Santa's place at the North Pole. In a one-room studio his five assistants busily craft games, puzzles, party hats, and clowny toss-boards, which are sold at the ice-cream parlor.

All this and more. A sign near the parlor's cash register invites customers to use other services offered by this we-aim-to-please place. Here, you can buy stamps and post letters - a big plus in Dar es Salaam, where waiting in line for stamps at the post office can easily cost you 45 minutes. You can use the telephone. You can stash your packages in a safe corner behind the counter while you explore the city. And if you stub your toe on a crumbling curb, there are bandages and ready consolation in this cheery oasis.

The effort the couple expends to make customers happy can seem larger than life in a city very short on the resources needed to do so.

''Unfortunately, we can't offer you a straw because there aren't any,'' Mr. Mullen says in apology. ''For a while we made our own, twisting paper strips and dipping them in wax. Now we can't find wax.'' He matter-of-factly comments that ''we're restricted to what we can get here. It's a daily scrounging. But you get used to it. You become flexible.''

His wife interjects, ''People complain about not being able to get a particular brand? We rarely have any type of chocolate. Chocolate is a banned item in Tanzania, because there is no in-country chocolate producer. There is a push for self-sufficiency in Tanzania, so only essentials are supposed to be imported. Chocolate is not seen as essential. When we do happen on some, it's an event, and we have a special festival.''

Chocolate or no chocolate, the Mullens offer a helping of sweet fantasy in a country hungry for a dream break or two.