In a food processor, add the egg yolk, buttermilk, and garlic. Pulse until combined.Next, drizzle in the olive oil until incorporated followed by the grated cheese and pepper. Puree until smooth. Season with kosher salt if needed.In a large skillet preheated to medium-high heat melt the butter. Add the peas and sauté for a few minutes or until warmed through. Turn off the heat and then toss in the cacio e pepper dressing.Transfer the peas to a plate and then add in arugula and avocado slices. Enjoy!