Add the cashews to the food processor and pulse a few times until crumbled. Add in spinach leaves, basil leaves, milk, lemon juice, and species, continue to pulse until leaves are finely chopped and everything is mixed.
In a pot with boiling and salted water cook pasta according to package instructions. Drain it and reserve½ cup of pasta water.
In a large pan over the medium heat add olive oil and shallot, stirring occasionally until onion is softened. Add the garlic and cook until the garlic is fragrant. Add in the cooked pasta with reserved pasta water and prepared pesto. Reduce the heat to medium-low and cook, stirring frequently, until the sauce has thickened slightly and is warm throughout.