Begin by melting the butter in a saucepan over low heat.
Add the flour into the melted butter and increase the heat to medium. Whisk the mixture and allow it to cook for 2 minutes.
Stir in the salt, garlic powder, and white pepper. Gradually pour in the cream and chicken broth while continuously whisking to combine the ingredients.
Allow the mixture to come to a simmer, whisking constantly as it heats. Once it begins to simmer, the sauce will thicken. It should be thick enough to coat the back of a spoon.
Remove the saucepan from heat and whisk in the lemon juice. To make the sauce thinner, add some pasta water or additional chicken broth if desired.