Bring a large pot of salted water to a boil. Cook the spaghetti according to package instructions and reserve 1/2 cup of the pasta cooking water. Drain the spaghetti and set aside.
Fry the Bacon:
Meanwhile, begin the sauce. Add the bacon to a wide pot and turn the heat to medium. Cook, stirring regularly, for 8-10 minutes or until all the fat is rendered and the bacon is crispy. Drain off all but 1 tablespoon of bacon fat.
Cook the Aromatics:
Add the butter to the bacon. Once melted and frothy, add onion to the bacon and cook for 10-12 minutes over low heat or until the onion is soft and translucent. If needed, season with salt and pepper.
Prepare the Dry Spice Mixture:
In a small bowl, combine all the ingredients for the dry spices.
Finish the Sauce:
Add the dry spice mixture to the pan along with the Roma tomatoes and cherry tomatoes and stir to combine. Cook over medium heat for 20 minutes or until the tomatoes are softened. Taste and season to your preferences.
Prepare the Gremolata:
As the sauce cooks, prepare the gremolata. Combine all the ingredients for the gremolata in a bowl and taste and season to your preferences. Set aside.
Finish the Spicy Spaghetti:
Pour the reserved pasta cooking water into the sauce and bring to a boil. Reduce heat, taste and season to your preferences, and then add the cooked pasta and toss to combine with the sauce until the spaghetti is glossy and coated. Turn off the heat.
To Serve:
Divide the pasta between bowls and pile the macadamia gremolata on top. Enjoy!