In a large pot over medium heat, melt the butter. Add the garlic, dried oregano, dried basil, onion powder, and a pinch of red pepper flakes; cook for 2–3 minutes until the garlic is fragrant.
Add 4 cups of water to the pot and increase heat to high to bring to a boil.
Once boiling, add 1 teaspoon kosher salt and the penne. Cook, stirring occasionally, for about 8 minutes until the pasta is nearly al dente; do not drain.
Reduce heat to medium-low and stir in the milk, heavy cream, and cream cheese. Cook, stirring, until the cream cheese melts and the pasta is al dente, about 4–5 minutes.
Remove the pot from heat and stir in the grated Parmesan until the sauce is smooth and creamy. Stir in the chopped parsley and season with additional salt and black pepper to taste.
Make the arugula salad by whisking together the olive oil, lemon juice, finely chopped shallot, and a pinch each of red pepper flakes, salt, and pepper in a small bowl.
Add the baby arugula and mixed fresh herbs to the dressing and toss to coat evenly.
Divide the creamy penne among bowls, top each serving with the dressed arugula and extra Parmesan if desired, and serve immediately.
