Meanwhile - use a blender to mix the egg yolks, sea urchin and parmesan cheese until well combined.
In a pot of salted boiling water, cook the paste until al dente then drain, reserving the paste cooking liquid.
Transfer the pasta into a large cold pan, add the egg and sea urchin mixture with a ladle of the pasta cooking liquid, then butter, speck fat and garlic.
Place over a low flame and toss the pasta until the egg mixture thickens to coat the pasta.
Transfer to a serving bowl and finish with the chopped chives, sea salt and some more parmesan.