To make the breadcrumb topping, in a nonstick pan over medium heat melt the butter. Once melted stir in breadcrumbs and coat in the butter, letting them toast for about 4 to 5 minutes. Remove from the pan into a bowl and add meyer lemon zest, stir to combine, and set aside while you make the pasta.
Prepare the meyer lemons by scrubbing them well. Trim the tops and bottoms off the meyer lemons and reserve them for squeezing on the finished servings. Slice the remainder of the lemons into ¼-inch discs, discard any seeds, then very roughly chop into small pebbly pieces.
Drain the cashews from the soaking water and add to a high-powered blender with fresh water. Blend until very very smooth and no pieces of cashews are visible.
Bring a large pot of water to a boil to cook bucatini. Generously salt the water once boiling and add the pasta. In the last minute of cooking add the peas if including them. Cook pasta to al dente. Reserve pasta water before draining. Do not rinse the pasta and peas.
Meanwhile, heat a large cast iron pan over medium-high heat. Once hot add the meyer lemon pieces in an even layer and do not toss for about 4 to 5 minutes. Allow the pieces to get charred and caramelized. Then toss and cook on the other sides for 2 to 3 minutes or until the lemons are looking evenly caramelized. Lower heat to medium and add vegan butter and toss around to coat the lemons as the butter melts, about 1 minute. Stir in garlic and ground dill, and cook another minute. Lower heat as necessary to prevent garlic from burning. Then over medium-low heat add in the cashew cream and allow to simmer, stirring occasionally, for about 2 minutes or until slightly thicker.
By now you should have drained pasta and peas. Add half the reserved pasta water and all the pasta. Toss to coat well, and add more pasta water as needed to make a smooth silky sauce. Stir in the fresh dill and sea salt and ground pepper to taste just before serving. Add more fresh dill and ground pepper as garnish. Add bread crumbs to each serving and add more as you eat the pasta so you get crispiness throughout!