Sandwiches can go south in any number of ways – and they usually do. The bread may be subpar, soggy, or both; the cheese and the meat pre-sliced, processed, inert; the mustard/mayonnaise applied with an overzealous hand; the lettuce succumbing to wilt; the filling jammed in the center leaving you eating mouthfuls of bread at the edges. Or the sandwich maker may simply suffer from a failure of imagination, handing you your 1,000th Brie and turkey sandwich, outfitted with sliced Granny Smith apples and honey mustard. Hello 1981.

The newly expanded Cheese Shop of Portland, at the edge of the culinary wonderland that is Washington Avenue, makes none of these mistakes. The entire menu (which changes seasonally) is five items long; it always includes grilled cheese. You can supplement your sandwich with bags of gourmet chips, and cap it off with dangerously luscious brownies ($3.75, easily enough for two eaters) or chocolate chip cookies ($3, ditto for the servings) from Night Moves bakery in Biddeford.

If this is your first visit, go straight for the store’s signature Ham & Butter ($9), made with justly famous Benton’s country ham, from Tennessee, and cultured butter. It’s extraordinary – salty, thinly shaved ham fused to a crusty Standard Baking baguette with double-sided lashings of butter so fluffy and flavorful I wondered if I’d ever tasted butter before. It wasn’t until I’d eaten half of the Ham & Butter that it occurred to me that there I was in a cheese shop eating a sandwich that had not a speck of cheese.

The pan bagnat, a classic Provencal sandwich ($7, or $10 with the addition of tuna) is almost as good. A couple of decades ago, if you asked an American chef about her cooking philosophy, chances are she’d say this: Start with good ingredients and get out of the way. That could be a textbook description of The Cheese Shop’s pan bagnat, made from chickpeas, black olives, shaved fennel, capers, tuna and Pecorino on a Standard Baking roll. Both parts and sum were faultless.

In its previous location, a cozy, narrow galley-shaped store in a renovated shipping container, the sandwiches were sold to go. When it outgrew that space, Will Sissle and his partner and wife, Mary Chapman Sissle, moved the business next door. The new location is a roomier, sunnier, pleasant spot with space for three tables – all occupied on a recent Tuesday at lunchtime. (The customers, who turned out to be wine importers, were lamenting proposed tariffs on wine.) The charming Dairy Cows of the World print that hangs behind the cheese counter made the move, too.

The short sandwich menu, by the way, doesn’t mean there are no distractions at the Cheese Shop. If you are anything like me, you will not get in and out quickly. Among the items for sale that nearly derailed both my workday and my budget were irregular nuggets of Rancho Gordo hominy; tiny, pearlescent fresh anchovies; still-warm loaves of Night Moves bread; hand-picked, quaintly boxed organic California dates; biscotti direct from Tuscany; Italian pine nuts (a scant handful for $14.99); and stacks and rows of persuasively labelled cheese, oh that cheese.

A perk of parking yourself to eat your sandwich? The Cheese Shop smells like heaven, which is to say, it smells pungently and splendidly like cheese.