1Preheat the oven to 350 degrees F. Butter sides and bottom of one 9-inch spring form pan.
2Mix together the sour cream and baking soda in a small bowl.
3Sift the flour and salt into another bowl.
4In the bowl of an electric mixer fitted with a paddle, cream the butter and sugar until fluffy. Add the almond paste, a little at a time, at medium speed, and beat for 8 minutes.
5Beat in the egg yolks one at a time, and mix until incorporated. It will look curdled; don't worry. Blend in the almond extract and sour cream mixture also add in lemon zest. Reduce mixer speed to low and gradually add the flour mixture, just until blended.
6Pour the batter into the prepared pan and spread evenly. Bake about 1 hour. It is done when you press the top and it returns to its shape, and also shrinks from the sides of the pan. Remove from the oven and place on a baking rack to cool in the pan. Serve as you like. Enjoy!!!!