Bring a large pot of salted water to a boil. Cook penne according to package directions until al dente. Reserve ¼ cup of pasta water, then drain.
In a large skillet over medium-low heat, melt the butter with the olive oil.
Add the minced garlic and cook for 30–45 seconds, just until fragrant. Do not brown.
Add the cooked penne to the skillet and toss to coat in the garlic butter.
Season with salt, black pepper, and red pepper flakes if using.
Add Parmesan cheese and toss gently. Use reserved pasta water a little at a time to loosen the sauce if needed.
Remove from heat. Garnish with fresh herbs and serve warm.