Bring a large pot of salted water to a boil. Wash and dry all produce. Peel and thinly slice shallot. Thinly slice garlic. Zest lemon until you have 1/2 tsp; quarter lemon. Roughly chop olives. Thinly slice chili.

Once water is boiling, add spaghetti to pot. Cook, stirring occasionally, until al dente, 9-11 minutes. Reserve 1/4 cup pasta cooking water, then drain.

Meanwhile, in a medium bowl, whisk together juice from 2 lemon wedges, a drizzle of olive oil, and lemon zest until combined. Stir in 1 TBSP shallot and season with salt and pepper.

Heat a large drizzle of olive oil in a large pan over medium heat. Add garlic, half the olives, and remaining shallot. Cook, stirring, until softened, 2-3 minutes. If desired, add a pinch of chili for spiciness; cook for 15 seconds. Add marinara and a pinch of salt and pepper. Bring to a simmer and cook for 2 minutes, stirring a couple of times. Turn off heat.

Add spaghetti to sauce, stirring to thoroughly coat. Stir in half the Parmesan and 2 TBSP butter. If sauce seems thick, add reserved pasta cooking water, 1 TBSP at a time, until loosened. Season with salt and pepper.

Add arugula to bowl with dressing; season with salt and pepper and toss to thoroughly coat. Divide pasta between bowls. Top with remaining olives and remaining Parmesan. If desired, sprinkle with a pinch of remaining chili. Serve with salad on the side. Serve with remaining lemon wedges for squeezing over.