Use either a stand mixer or an electric hand mixer, cream together the butter and the sugar.
Add the eggs, one at a time. Combine thoroughly. Scrape the bottom and sides of the mixing bowl occasionally with a rubber spatula.
Add the sour cream, lemon juice, lemon oil and combine. Scrape the bottom of the bowl again with a spatula.
Add half of the flour, baking powder, baking soda, and salt. Mix until the batter is smooth. Scrape the bottoms and sides of the mixing bowl and add the remaining flour mixture. Combine until the batter is smooth.
Fold in the blueberries using a spatula.
Place paper liners in 9x5-inch loaf pans. Divide the cake batter evenly into 2 prepared bread pans. Spread the cake batter out gently with a spatula.
Bake in a preheated 350 F degree oven for about 70 minutes. Or until a toothpick when inserted comes out clean, the cake is done.
Let the cakes cool for 10 minutes in the pan. Remove from the pan and let cool completely on a baking rack.
Mix together the icing ingredients in a medium size bowl with a whisk. Add more lemon juice for your desired thickness.
Once the cakes are completely cooled, spoon the icing over each cake. Let dry before putting cakes into twist tie bags.