Granny Edna's Lb Cake Recipe

I have decided to start the year off with my grandma's pound cake recipe!  I have tried this recipe many times in the pass only to be unsuccessful!  Coming from a long line of excellent cooks, this cake is a tradition for my family. Unfortunately, I have never been successful with this the pound cake recipe. Now, that I have The Kitchen Aide Artisan, I feel up for the challenge!

Granny Edna's Lb. Cake Recipe

3 sticks margarine
1 box confectionery sugar
6 large eggs
1 Tbsp.  vanilla
2 1/2 cups all-purpose flour

Cream butter, sugar, and flavoring well.
Add eggs, one at a time, beating mixture after each addition.
Add flour one cup at a time and beat 10 minutes at medium speed after each addition.
Bake 1 1/2 hours at 300 degrees.

I made a few changes in the recipe.  I used 1/2 Tbsp. lemon flavoring and 1/2 Tbsp. vanilla flavoring.  I also sifted the flour prior to adding it to the egg mixture. 
Enjoy!