Combine the ricotta, parm, egg, lemon zest and salt in a bowl. Add the flour and gently fold in until just combined. Dust with more flour, shape into a ball and place on a lightly floured surface.

Working in small sections, roll out the dough into a rope approximately ¾-inch thick. Using a knife or bench scraper, cut the rope into 1¼-inch pieces. Reserve on a lightly floured baking sheet and repeat until all the gnudi have been formed.

Melt the butter or oil in a large skillet. Add the mushrooms, season well with salt and pepper and cook over medium-high heat until lightly browned, about 5 to 7 minutes.

Add the garlic, toss lightly and cook until fragrant—about 30 seconds. Add the spinach, toss to coat and cook until just wilted.

While the sauce is cooking, bring a large pot of salted water to a boil. Working in batches, drop the gnudi into the water and cook at a high simmer until cooked through and tender—about 6 to 7 minutes.

Drain well and add to the sauce—tossing to coat. Cook for another 1 to 2 minutes, then spoon directly into serving bowls. Garnish with a little olive oil, grated Parmesan and cracked pepper.