Bring a large pot of heavily salted water to a boil. Add the pasta and cook al dente (timing depends on which type of pasta you use – I cooked the Banza chickpea pasta for 5 minutes). Strain, saving 1 ¼ cups of the pasta water, and rinse under cold running water, until room temperature.
In a large deep skillet over medium-high heat, add 3 tablespoons of the olive oil. When the oil is hot, add the garlic, sausage, and red pepper flakes. Cook for 6 minutes, stirring often, until nicely browned. Add the kale and cook for one minute, then add the caramelized fennel and oregano and cook for an additional minute.
Add the pasta, saved pasta water, and the rest of the olive oil. Cook for 1 minute, until most of the liquid is absorbed. Taste and adjust seasoning. Serve with the toasted breadcrumbs sprinkled on top.