Method

• 1.
  Bring a large pot of salted water to a boil for the pasta.
• 2.
  In a large frypan, melt butter over medium heat until foaming. Add bread, season with salt and pepper, and cook, tossing, until golden brown and toasted, 4 to 5 minutes. Transfer breadcrumbs to a medium bowl or plate, add lemon zest and parsley, and toss to combine.
• 3.
  Wipe out frypan and return to mediumhigh heat. Add olive oil and when shimmering, add sausage. Use a wooden spoon to break into 2.5-5cm pieces and cook, undisturbed, until dark golden brown on underside, 5-7 minutes. Use the spoon to scrape up sausage, then toss quickly to get a little heat on all sides. Use a slotted spoon to transfer to a plate. Add garlic to drippings in pan, remove from heat, and stir to coat (there should be enough residual heat to soften the garlic almost immediately). Place frypan aside. Add cauliflower to boiling water and cook until tender all the way through but not mushy, 4-6 minutes. Use a slotted spoon to transfer to frypan with garlic and stir to coat with oil.

• 4.
  Add pasta to same pot of boiling water and set a timer for 2-3 minutes less than packet instructions (it should be very al dente and will finish cooking in the sauce). Use a slotted spoon to transfer pasta to frypan with cauliflower. Add browned sausage and return frypan to medium heat. Cook, tossing and adding spoonfuls of pasta water into mixture, until pan sauce starts to cling to noodles.
• 5.
  Add Parmigiano Reggiano and continue to cook, tossing and moistening with pasta water as needed, until cheese is melted and pan sauce is glossy and abundant. Add lemon juice and half of reserved breadcrumbs and toss to combine. Serve pasta with remaining breadcrumbs on top and more Parmigiano Reggiano on the side.