Place the bacon in a large skillet and cook over medium-high heat, turning occasionally, until evenly browned, about 10 minutes. Drain the bacon slices on paper towels. Crumble bacon when cooled.

Heat olive oil in a large skillet over medium heat; cook and stir crumbled bacon and onion in the hot oil until onion is translucent, about 5 minutes. Stir chicken into mixture and season with garlic powder, salt, and black pepper. Cook and stir until chicken is no longer pink inside and lightly browned outside, about 10 minutes.

Stir sun-dried tomatoes and pesto in a large skillet over medium heat until pesto gives off a little oil, about 2 minutes; stir in spinach and cook until wilted, stirring constantly.

Mix mascarpone cheese, 2 cloves of garlic, Dijon mustard, lemon juice, milk, and white pepper in a saucepan over medium heat. Cook until smooth and bubbling, stirring constantly, about 5 minutes; stir in 1/2 cup Parmesan cheese until cheese has melted, 2 to 3 more minutes. Pour sauce over chicken and bacon mixture.

Bring a large pot of lightly salted water to a boil. Cook bow-tie pasta at a boil, stirring occasionally, until cooked through yet firm to the bite, about 12 minutes; drain. Gently fold pasta into chicken mixture and transfer to a serving bowl. Top with spinach mixture and sprinkle with 1 more tablespoon Parmesan cheese, or to taste.