In a large skillet, heat the oil until it reaches 350 F.
Trim the chicken thighs and flatten them.
Place the chicken between parchment paper and gently roll it out to even thickness.
Prepare a breading station with flour, eggs, and seasoned breadcrumbs mixed with Parmesan cheese.
Dredge the chicken in flour, dip it in the egg wash, and coat it with the seasoned breadcrumbs mixture. Press the breadcrumbs firmly onto the chicken and let it rest for about 10 minutes.
Cook the spaghetti in boiling water with olive oil and salt until al dente.
When the oil reaches 350 F, fry and cook the chicken thighs in the skillet for about 2 and a half minutes on each side until golden brown and cooked through. Note: You can cook 3 chicken thighs at a time. If using a skillet, cook for 4 minutes on one side, and an additional 2 minutes when flipping sides.
Once cooked, top the chicken with butter to brown the breadcrumbs further.
Finish the chicken by topping it with marinara sauce and mozzarella cheese, then bake until the cheese is melted and bubbly.
Meanwhile, sauté the broccoli rabe with olive oil, chili flakes, and lemon juice until tender-crisp.
Drain the cooked spaghetti and toss it with olive oil, salt, pepper, fresh parsley, and a small amount of marinara sauce.
To plate, arrange the broccoli rabe in the center of the plate, top with marinara sauce, then place the chicken Parmesan on top. Serve with the seasoned spaghetti and garnish with freshly grated aged Parmesan cheese.