In a large pot over medium heat, toast cloves, cardamom, star anise, chiles, cinnamon, and peppercorns, turning until fragrant, about 2 minutes.
Add in cilantro, shallots, garlic, two pieces of your lemongrass, one ginger, broth, and fish sauce and bring to a boil.
Reduce heat; simmer for roughly 1–1 ½ hours.
Strain into a large bowl, pressing on solids.
Return broth to pot; season with salt and pepper.
Pulse cashews in a food processor until finely ground.
Add your shallot, chile, 1 piece of lemongrass, ginger, brown sugar, and shrimp paste; process until smooth.
Heat oil in a small skillet over medium and cook paste, stirring, until it starts to brown, about 2 minutes.
Cook noodles according to the package directions.
Drain; rinse under cold water.
Bring broth to a simmer, add shrimp, and cook until cooked through, about 2 minutes.
Divide noodles among bowls. Add 2 Tbsp. paste to each and ladle broth over; stir to incorporate paste.
Top with shrimp, sprouts, scallions, and your choice of fresh herbs; season with pepper.
Serve with chili oil and lime wedges for your own personal taste and preference.