Bring a large pot of salted water to a boil. Cook penne according to package directions until al dente. Reserve ¼ cup pasta water, then drain.
While the pasta cooks, add roasted red peppers to a blender or food processor and blend until smooth. Set aside.
In a large skillet over medium heat, melt butter with olive oil. Add garlic and cook for 30 seconds, just until fragrant.
Stir in the blended roasted red pepper sauce and simmer gently for 2–3 minutes.
Reduce heat to low and stir in heavy cream, Parmesan cheese, salt, black pepper, smoked paprika, and red pepper flakes if using.
Add the cooked penne to the skillet and toss to coat. Use reserved pasta water a little at a time to loosen the sauce if needed.
Remove from heat and garnish with fresh herbs before serving.