Preheat your oven to 425 degrees F.
Wash and dry the asparagus, then cut into 1 - 1 1/2 inch sized pieces. Toss with a drizzle of olive oil, and a pinch each of salt and pepper.
Bake asparagus in the oven for 10 minutes. When done, remove from the oven, but keep the oven heated at 425 degrees F.
While the asparagus is cooking, boil your pasta in SALTED water until al dente. When done, drain the water.
Keeping your pasta in the pot, add in the pesto and mix until all the pasta is evenly coated. Then, stir in the asparagus, arugula, and mozzarella.
Transfer the pasta mixture into an oven-safe cast iron skillet, pie dish, or casserole dish.
Bake pasta in the oven at 425 degrees F for 15 minutes.
When done, remove the pasta bake from the oven and let cool. Garnish with extra arugula, if you'd like.
Enjoy!