Melt butter in a medium saucepan over low heat. Cook and stir the shallots until they become translucent and tender; stir in garlic and cook until tender and aromatic.
Stir in 1 cup white wine, increase heat to high and bring to a boil. Once it boils, add the remaining 1/2 cup wine. Boil for 10 minutes then reduce heat to medium-low. Season with white pepper to taste.
When sauce is no longer boiling, slowly stir in cream, lemon juice and salt. Simmer for 3 to 5 minutes.