In the bowl of a mixer, combine butter and sugar and beat well to combine (mixture will be fairly dry).
Add in eggs and beat until well combined.
Add sour cream, vanilla and lemon extracts, lemon zest and lemon juice and beat until well combined.
In a separate bowl combine flour, baking powder, baking soda and salt.
Add dry ingredients to wet ingredients and mix on low until combined, but do not over mix.
Pour batter into a greased and lined 9x5 loaf pan. Bake for approximately 45 minutes or until a cake tester inserted into the center of the loaf comes out clean. If loaf does not see done at 45 minutes but is browning, foil can be placed loosely over the top to allow more baking time without additional browning. Remove from oven and allow to cool.
Combine icing ingredients in a bowl and mix until combined. If a thicker icing is desired, add more powdered sugar, one tablespoon at a time. If a thinner icing is desired, add more milk, one teaspoon at a time. Remove loaf from pan (it helps to run a knife around the edges first to make sure the loaf isn't sticking to the pan) and pour or spoon glaze over the top. Allow icing to set up for 20+ minutes, then slice and serve.
Notes
To substitute sour cream use same qty full fat plain yogurt.Since I didn't use lemon extract, I used 2 tbsp of lemon juice instead of 1 tbsp. Pour the icing over the cake only after the cake is cooled completely.