Restaurant Review: UpStairs on the Square in Cambridge

“Green” pizza, Monday Club Bar, $13

The Monday Club Bar, which strikes an ideal balance between a laid-back bar and an ambitious grownup restaurant, is the more changed of the two. There’s a new “food bar,” a small open kitchen on one side with a few high seats for casual diners, and a new pizza oven. The dishes emerging from the kitchen and oven are straightforward and satisfying, and suit pretty much any mood—though not any budget. Despite the informal feel, main courses at the Monday Club Bar are priced like those at a high-end restaurant.

The new oven does justice to the laboriously made pizzas. Over the course of three days, the slightly oiled dough is gently folded to allow for slow fermentation. The result is a crust that is wonderfully blistered, bubbly, and resilient. The toppings transform these pies into full meals. The lobster pizzetta ($19), for instance, features a lobster-stock base thickened with cream, Parmesan, and ricotta salata, as well as nubs of crustacean meat. “Green” pizza ($13) is similarly rich, with soft Robiola cheese that melts into a white bed for spinach, the whole thing lightened by a sprinkling of lemony sorrel leaves. You won’t want anything else except for dessert.

Nor will you need more after cozy first courses like the tomato soup and grilled cheese ($11), which is perfect for a cold night: Though the cream-based soup is bland (albeit freshly made), the sandwich redefines grilled cheese—buttery slices of homemade brioche browned in a panini press, with just a good slab of Grafton cheddar in between. The Parmesan polpettini ($11), spheres of garlicky bread crumbs and egg in a “savory brodo,” live up to their name: bacon, pancetta, mushroom stems, and Parmesan can only explode into an umami bomb, and these do.

Main courses are reliable, particularly a cioppino ($23) that varies with seasonal fish and seafood, showcased in a thick broth based on lobster stock and red peppers, with a smear of creamy, saffron-y rouille. One entrée is exceptional: orange-and-pepper-cured duck ($27), the breast cut thin and, unusually, on the long side, which in other hands could toughen the slices. A rillette of duck-leg confit, usually the fatty standby that compensates for dry breast meat, plays a welcome supporting role to the breast.

The food in the swanky Soirée Dining Room, meanwhile, has the same out-of-time feel as ever, with fancified fare that could be from a dinner party in the late ’70s. Regis’s mastery of pasta is on display here, specifically in a first course of postage-stamp-size agnolotti filled with beet and ricotta ($14). The warm, shallow layer of melted butter on the plate is something you might find in, say, Parma—though with the un-Italian, and inspired, addition of butter-toasted pistachios.

Cioppino, Monday Club Bar, $23