In the same pot on medium-high heat, add butter and oil, and heat until butter is melted.
Add the flour and using a whisk, cook it for 1 minute.
Then gradually add milk while whisking continuously to prevent lumps. Keep whisking until all the lumps disappear.
Now add salt, black pepper powder, paprika, and chicken bullion cube.
Cook until the sauce thickens. This will take around 3-5 minutes. Make sure to stir continuously or the sauce will burn.
Once thickened, add the sauce to the pasta in the baking dish, along with 1/2 cup cheese, and mix very well