Place bacon in a large skillet and cook over medium-high heat, turning occasionally, until crispy, about 10 minutes. Drain bacon slices on paper towels. Reserve 2 tablespoons bacon grease in the skillet.

Add onion to the skillet over medium heat. Cook until golden, 5 to 10 minutes. Add mushrooms and garlic and cook until browned, about 10 minutes more. Add grilled chicken and zucchini to the skillet and cook until zucchini are cooked through, yet still firm, 5 to 10 minutes more.

Remove skillet from heat, add tomatoes, and let sit until tomatoes are warm, about 5 minutes.

Meanwhile, bring a large pot of lightly salted water to a boil. Add penne and cook, stirring occasionally, until tender yet firm to the bite, about 11 minutes. Drain and transfer to a large serving bowl.

Combine vegetable mixture with drained pasta. Stir in Parmesan cheese and season with black pepper.