Cook pasta according to package instructions, reserve 1 cup of the pasta water when you drain it you may use it later.
Start by making your pesto, in a food processor add basil, arugula, jalapeño, 1 garlic clove, nuts, parmesan, olive oil and salt to taste. Pulse it until you get a nice sauce.
In a large bowl add drained pasta, pesto, coconut milk and toss to combine. If you would like the sauce thinned a little bit use some of the reserved pasta water.
In a pan skillet heat a couple tablespoons of olive oil, add in butter until melted then add cajun seasoning and pepper to taste. Add scallops and sear on each side cooking for only a couple minutes on each side.