How to make the spinach dip sauce: In a small saucepan on medium heat, melt 2 tablespoons butter. Add 2 tablespoons minced shallots and 1 tablespoon minced garlic. Saute for 3 minutes. Slowly whisk in 3 tablespoons all-purpose flour to make a roux. Cook 4 minutes. While stirring, add 16 ounces (2 cups) heavy cream, 1 teaspoon ground white pepper, 1 teaspoon salt, 1/4 cup finely juliennned fresh basil and 1/4 cup freshly shredded Parmesan cheese. Bring to a boil. Reduce the temperature to low and simmer for 6 minutes, stirring constantly to avoid sticking. Place the sauce in the refrigerator to cool until ready to assemble dip.