Preheat oven to 350 degrees F. Generously spray a 10-inch tube pan with baking spray with flour.
In the bowl of a stand mixer fitted with the paddle attachment, cream softened butter and granulated sugar at medium speed for 5 minutes until light and fluffy, stopping to scape down the sides of the bowl.
Add egg yolks, one at a time, mixing well between each addition
Add lemon extract and lemon zest, mix to combine
In a large bowl, sift together flour, baking soda and salt.
Add flour mixture alternatively with buttermilk, beginning and ending with flour mixture, beating just until combined after each addition.
In a separate bowl, beat egg whites until stiff peaks form. Using a rubber spatula, gently fold egg whites into batter. Pour batter into prepared greased 10-inch tube pan.
Bake for 1 hour to an 1 hour and 10 minutes. Or until cake tester comes out clean and cake bounces back when lightly pressed. Let cake cool in pan on wire rack for 10 minutes. Invert and remove from pan. Let cake cool completely on a wire rack.