Preheat the oven to 250 degrees.
In one bowl, cream butter and flour with a pie crust creamer until it resembles corn meal.
In the bowl of a standing mixer, beat eggs until thick and lemon colored.
Add sugar, mixing until combined. (after adding 1st cup sugar to eggs, beat about 1 minute; add 2nd cup of sugar and beat a minute more.
Add flour and butter mixture to egg mixture. On top of this, add salt, baking powder, lemon zest, lemon juice, vanilla extract and sherry.
Beat for 5 minutes on high.
Spray pans with nonstick spray, then flour all sides. Pour in two regular bread/loaf pans. Bake at 250 degrees for 30 minutes. Then raise oven temperature to 325 degrees and bake for 40 minutes. Cool on baking rack.
If using a bundt pan, bake at 250 degrees for 40 minutes and then at 325 degrees for 1 hour. Cool on baking rack.