Cook the pasta according to package instructions (I simply boil the macaroni shells in boiling salted water for about 8 to 9 minutes or according to time mentioned in the package instructions for al dente cooked pasta).
While simmering the pasta, add the pasta shells only once the water comes to a boil and make sure the pasta shells are immersed in water.
Once you start simmering the shells, use medium heat and make sure to stir in between so the shells won't be stuck.
Once the pasta is cooked, drain the water, add one tablespoon olive oil, 4 tablespoons of butter and also the shredded cheddar cheese to the cooked hot pasta, stir gently to combine and keep the pasta aside.
In a large bowl, place the cream cheese and whisk the cream cheese very well.
Also add sour cream and mix well to combine with cream cheese. If necessary, you can use an electric mixer for about a minute to combine the cream cheese and sour cream, but this is not necessary.
Once the cream cheese sour cream mixture is prepared add this mixture to the cooked pasta, add the remaining one tablespoon of olive oil and stir gently to combine with the pasta to make creamy, delicious mac and cheese with cream cheese, cheddar cheese and sour cream.