In a food processor add basil, lemon juice, garlic, 1 cup parmesan, salt, pepper, chili flakes, and kelp cubes. Blitz for 10 seconds, add olive oil and blitz for 1 minutes. Taste and adjust seasoning.
Heat a sauce pan over medium heat, then melt butter and stir in flour, pour half and half in thirds. Make sure there’s no lumps. Add parmesan. Bring to a boil and stir occasionally making sure cheese is fully melted.
In a 9 x 13 pan, add a few spoonfuls of cream sauce to bottom of pan and spread evenly across. Then layer a few pieces of lasagna to cover the pan, a layer of pesto, crabmeat, spinach, ¼ cup of sauce and shredded cheese, repeat to the top layer.
Pop in oven and reduce heat to 350 F for 30 minutes. Remove from oven and garnish with parsley.