L’Impasto means “the dough” in Italian, and Passini is clearly passionate about the concept. His breads and pastas are exquisite, from airy focaccia laden with fontina cheese and wild mushrooms to pillows of ravioli filled with creamy whipped potatoes and nutty piave cheese, swimming in butter and sage. The fact that he does all the shopping, prep work, and baking himself, and prepares each dish on the menu in a tiny open kitchen, makes it all the more impressive.

Passini, 39, opened L’Impasto a little over a year ago after spending five years in the kitchen at Ristorante Fiore in the North End. It’s a cozy 20-seat spot, with tiny copper pots hanging on the yellow walls alongside black-and-white pictures of an Italian movie star eating giant forkfuls of spaghetti. It’s so cozy, in fact, that there’s nowhere to wait, which you very well might have to do on the weekends. Four of us ended up sitting in the car on a chilly Saturday night, thankful when the server called 15 minutes later.

With a skeleton crew — only Passini, a server, and a dishwasher during the week — the service is slow, and informal. One night we asked twice for a knife that never came, and our water glasses went dry. Another time we waited 20 minutes to be asked what we wanted to eat. When we weren’t sure which wine to order — even though the selection is limited, with six $30 bottles to choose from — the server brought out three open bottles and let us decide. Later, after the meal service had ended, we saw the server at the stove, cooking himself a meal of mussels and pappardelle.

Passini is a constant presence, cooking in his shirt sleeves as he ladles sauce out of large plastic containers and stirs bubbling pots on his eight-burner stove. His soundtrack ranges from American pop to complete silence, which made the place disturbingly quiet one weeknight when a friend and I were the only ones in the restaurant.

Passini recently revamped his menu, changing nearly every item on it. The pizzas weren’t selling, so he axed them altogether — a wise move considering the Napoletana with tomato sauce and buffalo mozzarella was fairly forgettable. But I was sorry to see the Caesar salad go — a crisp, garlicky creation served with addictive anchovy-Parmesan toast.

He replaced a white lasagna with wild mushrooms, Swiss chard, and mascarpone with a subtle but superior lasagna with Bolognese sauce balanced by a creamy bechamel, the protruding noodles charred to a lovely crisp. Toothsome gnochetti sardi now come with a hearty lamb ragu instead of clams and broccoli rabe, and the spinach-ricotta cannelloni has been transformed into a sweet, creamy dish filled with ricotta and mascarpone topped with butternut squash.

Thankfully, Passini kept the satisfying bucatini alla matriciana, a traditional Roman dish with a white wine and tomato sauce thickened into meaty goodness with pancetta. He also held on to a basic eggplant Parmigiana and veal scaloppine with prosciutto, sage, and white wine that has a sweet, almost apple-y flavor.

The starters are hit and miss. A special of burrata stuffed with mascarpone, wrapped in prosciutto, and finished with balsamic-soaked grape tomatoes is creamy, salty, tangy perfection. Lightly fried salt cod and potato croquettes play well with pickled sweet peppers and lemony aioli, and a salad of sweet beets, licoricey fennel, and bitter radicchio offers a jolt of refreshing flavors.

But the pan-seared scamorza mozzarella, served with crostini and prosciutto, quickly hardens into a rubbery block, and fennel salad with smoked salmon and olives tastes only of smoked salmon — both selections from the old menu. Golden nuggets of gently fried ricotta are nice, but undermined by bitter slices of eggplant; discs of formerly crispy Parmesan get soggy when mixed with prosciutto and endive.