Bring a large pot of salted water to a boil. Add the penne pasta and cook according to package instructions until al dente, about 10-12 minutes. Drain and set aside.
While the pasta cooks, prepare the pesto. In a food processor, combine the fresh basil leaves, 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.
Add the grated Parmesan cheese, salt, and black pepper to the food processor and pulse a few more times to combine. Set the pesto aside.
In a large skillet over medium heat, melt the unsalted butter. Pour in the heavy cream and bring to a gentle simmer, stirring frequently.
Reduce the heat to low and stir in the prepared pesto. Cook the sauce for 2-3 minutes until heated through and slightly thickened.
Add the drained pasta to the skillet with the creamy pesto sauce. Toss well to coat the pasta evenly with the sauce.
Remove from heat and serve immediately. Optionally, garnish with extra grated Parmesan and a few fresh basil leaves.