Preheat oven to 325 degrees F. Spray a light-colored tube pan or 12 cup (10 inch) Bundt pan with flour-added cooking spray.
Mix together the cake flour and salt. Set aside. If using poppy seeds, add them to the cake flour.In the bowl of a stand mixer, beat the butter, cream cheese and sugar for a good 5 to 8 minutes, scraping down the sides of the bowl occasionally.
Add the egg yolks and beat for another 2 minutes or so. Beat in the lemon zest and lemon oil, scraping down sides of bowl periodically.Stir, do not beat, in the flour/salt mixture.In a separate bowl, beat the egg whites until soft peaks form. Fold the beaten egg whites into the cake batter, then pour into the greased pan.
Bake the cake for 60-80 minutes or until a long skewer inserted in center comes out clean (internal temperature 210 F) or with moist crumbs as opposed to batter.
Let cool in pan for 10 minutes, then invert and allow cake to cool completely on a rack.To make the glaze, melt the butter in a large 2 cup microwave-safe measuring cup.
Add the powdered sugar and stir to coat. Now add the lemon juice a teaspoon at a time, stirring, until glaze is a good consistency for drizzling.
Drizzle over the cake by pouring it straight out of the measuring cup.
