make the cake:
Cream butter and sugar until light and fluffy.
Add eggs, 6 of them, one at a time., beating well after each addition.
Stir in lemon juice, lemon peel and extract.
Sift together flour, baking soda and salt.
Add the flour mixture to the batter alternately with the sour cream. Beat until combined and pour into a greased and floured tube pan. Bake at 350 degrees. Marie's recipe said to bake for 55-60 minutes or until toothpick comes out clean. I had to bake 80 minutes. Stoves bake differently. You really need to rely on your doneness test instead of the time. Remove from oven and let sit for 10 minutes before removing from the tube pan. Let cake cook completely on a wire rack before icing. Once it's completely cooled, pour on the glaze.
make the glaze:
Beat butter and sour cream in a small bowl until smooth. Slowly add confectioners sugar. Stir in lemon juice and lemon peel. Pour over cooled cake.