This is what I would do...

use water rather than milk, the grated rind from 1 lemon and lemon extract instead of vanilla

Should be yummy!

Nancy

I'm not a fan of lemon extract....I think it tastes phony.
I would make the recipe as stated, with the vanilla and add lots....perhaps 2 lemon's worth of grated rind.
And if you thought she would like it, I would mix the juice of one of those 2 lemons with about 1/2 cup of powdered sugar and after the cake is baked, poke holes with a tooth pick or a wooden skewer and pour that glaze slowly over the cake, allowing it to soak in before you add more.
Linda C

I like the lemon glaze idea, but I'd also go with the substitution of lemon extract for the vanilla OR I'd sub lemon juice for about half the milk (keeping the liquid amount the same as the original recipe), add the zest and then glaze it.

Then again, I love lemon and never believe anything has too much lemon in it.

Annie

I have to agree about the artificial taste of lemon extract. Since there's some disagreement about that just among us here, you may want to check with your friend to see if she's got any strong feelings one way or the other.

As to using juice--don't. If you sub lemon juice for (part of/all) the milk in the recipe, that totally changes the chemistry. The cake will flop unless you then adjust the leavening. Lemon juice is acid, this cake is leavened with baking powder (a combo of baking soda and acid)--so use lemon juice and you'll have TOO much acid for the baking soda to work properly. You'd need to figure out how much baking soda to add to work with the lemon juice and how much less baking powder to use. I don't have a formula for that, and you'd probably have to do several test cakes to get it exactly right if you start fiddling around with the acid/base balance of the recipe.

I'd go with lemon peel, and then, when the cake was done and still warm, maybe poke it and pour some lemon-flavored simple syrup over so that the flavor soaks all through the cake. Alternatively, you could make up some lemon pudding, and pour that over the poked cake for extra moistness and flavor.

That's why I didn't suggest adding lemon juice. What I believe would happen is that the cake batter would "fizz" up immediatly and then not rise at all in the oven.....but I'm not willing to waste all the time and effort to try it out.

Well, maybe, but this is one of my favorite lemon cake recipes, from "Joy of Baking" and it has 1/4 cup of lemon juice in addition to lemon zest AND lemon extract but has TWO teaspoons of baking powder instead of the one in the above recipe. Very lemon-y but not fluffy...

Lemon Cake

1 cup (226 grams) unsalted butter, room temperature

1 cup (200 grams) granulated white sugar

4 large eggs

1 teaspoon pure vanilla extract

Zest of 1 large lemon

2 cups (280 grams) all purpose flour

2 teaspoons baking powder

1/4 teaspoon salt

1/4 cup (60 ml) fresh lemon juice

Icing:

1 cup (115 grams) confectioners' (powdered or icing) sugar, sifted

2 tablespoons fresh lemon juice

Preheat oven to 350 degrees F (180 degrees C) and place rack in the center of the oven. Butter, or spray with a nonstick spray, a 9 inch (23 cm) springform pan and then line the bottom of the pan with parchment paper. Set aside.

In the bowl of your electric mixer, with the paddle attachment, cream the butter and sugar until light and fluffy and pale in color (about 3 minutes). Add the eggs, one at a time, mixing well after each addition. Beat in the vanilla extract and lemon zest.

Sift together the flour, baking powder and salt and then add to the batter along with the lemon juice. Mix only until incorporated.

Pour the batter into the prepared pan, smoothing the top with an offset spatula. Bake about 45 minutes, or until a toothpick inserted in the center comes out clean. Place on a wire rack to cool, then gently remove the sides of the pan.

For the icing, combine the sifted confectioners' sugar with the 2 tablespoons lemon juice. (You want the icing to be thicker than a glaze but still thin enough that it will just run over the sides of the cake. If not the right consistency add more lemon juice or powdered sugar, accordingly.) Frost the top of the cake, allowing the icing to drip down the sides. Let the icing set before covering.

This cake will keep for several days in an airtight container.

Makes one - 9 inch (23 cm) cake.

Annie

Thanks for all your input. I think I'm going to add lemon zest to the batter, use the vanilla extract and then do the glaze and hole method with the lemon juice and sugar.

I won't be making it until next week but will let you know how it turns out.

Annie, your recipe sounds good but one reason she requested the sponge cake is she keeps to a lower fat diet and that would be too much butter for her.

Ruthanna, I just posted that recipe because it uses lemon juice, because some posters were afraid the lemon juice would affect the leavening.

It might, because the recipe requires twice as much baking powder, but I still think lemon juice could be used successfully, maybe with a bit more leavening and could take the place of artificial lemon extract if the flavor of that is bothersome.

Annie