Notes: Look for high-quality fresh sausage; the casings will be easier to remove. Ricotta salata is available at specialty food stores and some well-stocked supermarkets; if you can't find it, substitute 2 ounces crumbled feta cheese.
12 ounces dried orecchiette pasta
3 tablespoons butter
1 onion (8 oz.), peeled and chopped
2 large cloves garlic, peeled and minced
1/4 teaspoon hot chili flakes
8 ounces chicken sausages, removed from casings and crumbled (see notes)
4 ounces ricotta salata cheese, thinly sliced or crumbled (see notes)
How to Make It
In a 5- to 6-quart pan over high heat, bring 4 quarts water to a boil. Add pasta and cook, stirring occasionally, until tender to bite, 12 to 15 minutes. Drain.
Meanwhile, in a 12-inch frying pan or a 4- to 5-quart pan over medium-high heat, melt butter. Add onion and stir often until lightly browned around the edges, 8 to 10 minutes.
Lower heat to medium and add garlic, chili flakes, and crumbled chicken sausages. Stir with a wooden spoon, breaking up sausage if necessary, until meat is beginning to brown, 5 to 10 minutes; if garlic begins to scorch, lower heat.
Add tomatoes and spinach; stir until spinach is wilted, about 2 minutes.
In a large bowl, mix pasta and sauce to coat; top with ricotta salata.