Bring a large pot of salted water to a boil. Add the penne pasta and cook according to package instructions until al dente, about 11 minutes. Drain and set aside.
While the pasta cooks, prepare the pesto. In a food processor, combine the fresh basil leaves, 1/4 cup grated Parmesan cheese, pine nuts, and garlic cloves. Pulse until finely chopped.
With the food processor running, slowly drizzle in the olive oil until the mixture is smooth and emulsified. Season with 1/2 teaspoon salt and 1/4 teaspoon black pepper. Set aside.
In a large skillet over medium heat, melt the unsalted butter. Add the heavy cream and bring to a gentle simmer, stirring frequently.
Stir in 1/2 cup grated Parmesan cheese until melted and the sauce is smooth and slightly thickened, about 3 minutes.
Add the prepared pesto to the cream sauce and stir to combine evenly.
Add the drained pasta to the skillet and toss well to coat the pasta thoroughly with the creamy pesto sauce.
Cook for an additional 1-2 minutes to heat through, then remove from heat.
Serve immediately, garnished with extra Parmesan cheese if desired.