Grease and flour a 9x5-inch loaf pan and preheat the oven to 350 F.
Whisk together the dry ingredients in a medium-sized bowl: flour, lemon pudding, baking powder, baking soda, and a pinch of salt.
Using a hand-held or stand mixer, beat the eggs, sugar, vanilla extract, lemon extract, lemon juice, lemon zest, oil, and yogurt until smooth.
Gradually beat the dry ingredients into the wet just until combined.
Pour the batter into the loaf pan and bake for 55-60 minutes or until a toothpick inserted in the middle comes out clean.
Let the loaf cool inside the pan for about 10 minutes, unmold, transfer to a cooling rack, and let cool completely.
Prepare the icing: beat the butter and lemon juice with a hand-held or stand mixer until smooth. Gradually add the powdered sugar and beat until creamy.
Spread the frosting evenly over the loaf. This recipe makes enough icing to cover the whole loaf, so spread it on the top, and it will fall down the sides on its own. Before serving, refrigerate until the frosting sets.