In a medium bowl, beat the softened cream cheese, ricotta, sour cream, 1/4 cup parmesan, garlic powder, and fresh basil until silky and smooth.
Toss cooked spaghetti with half of the warm meat sauce. Spread half of the saucy spaghetti in the bottom of the prepared baking dish.
Spread the entire cream cheese and ricotta mixture evenly over the pasta layer.
Top with the remaining saucy spaghetti, then spoon the remaining meat sauce evenly over top.
Cover with shredded mozzarella and remaining 1/4 cup parmesan.
Cover loosely with tented foil. Bake at 375°F for 25 minutes. Remove foil and bake 15 minutes longer until cheese is melted and bubbling with golden brown spots. Let rest for 10 minutes before slicing.