Hello all,
  My husband’s birthday cake request this year was “white cake, strawberry filling, and buttercream frosting”.  I am confident and capable with two of those things, however I am sort of stumped about the strawberry filling.  I envisioned something with the flavor intensity of lemon curd, but in a strawberry version, but don’t know how to get there.  I am still a very tentative baker, as my failures don’t always turn out as palatable lessons and I HATE to waste food.  Sometimes I just make “lessons that end up in the garbage” so I am not eager to just start trying stuff.
  His birthday is March 28, so there is time to learn a new trick or two, but I need guidance.  My plan so far is White Velvet Butter Cake and Mousseline buttercream.  I have made the neoclassic several times, but after reading the raves for the flavor of the mousseline, and since his decoration request requires the whitest possible surface, I’m going with the that. 
  He wants it to be just a thickened fruit filling, not buttercream or whipped cream flavored with, or containing chunks of berries.  It sounds simple enough, but my brain locked up on me when I started to think about how to do it, and that horrid jelly-like stuff they use to fill grocery store cakes leapt into my mind . 
  Please let me know what you think might work.  Or better yet, what has worked for you in the past.  I have TCB, but Heavenly Cakes isn’t going to be gracing my shelf for another month or two. 

Thank you so much,
                  Melanie

Rose has a recipe for strawberry conserve in Cake Bible (p. 333). I’ve made it many times, and it is delicious—nothing like the supermarket stuff. Her notes say that if you increase the sugar, you can use it to spread on toast. I don’t see why it wouldn’t work as a filling for the cake. The worst that will happen is that some of the conserve will soak into the cake layers, acting as a syrup, which is not a bad thing.

When filling the cake, it will be necessary to pipe a dam of buttercream around the perimeter of the first layer so that the conserve doesn’t ooze out later when you stack with the second layer.

Another idea is to fill the cake with fresh strawberries nestled in buttercream.

Christine S.
  Thank you for the quick reply!  I had seen the conserve recipe in the cake bible, but was a little uncertain of its consistency.  I am glad to know it could work.  I’ve made the raspberry version of Rose’s fruit puree, but haven’t tried it with strawberries, and haven’t worked my way up to the conserve, (it seems a little more complicated). 
  I had suggested the strawberries could be embedded in the frosting between the layers, but the response was less than enthusiastic.  I think he’s worried it will take on a custard character.  For now, I’ll try to make the pure fruit filling work.  I’d still like to avoid the buttercream barrier, if at all possible.  Maybe I’ll fiddle around with thickening the conserve, or maybe the puree.  I’ll try to post back with any successes I may have on that front.  Otherwise, I’ll surely be back with follow-up questions

I’ll offer two suggestions - the first is to fill the cake with strawberry mousseline using Rose’s strawberry puree.  It’s amazing!!  The second is fill the cake with sugar macerated diced strawberries stirred into vanilla mousseline.  Also amazing!!  I’ve done both on several occasions and there are never leftovers to bring home.

Whatever you do, I’d definitely suggest using a buttercream dam around the perimeter of your filling - your asking for trouble if you omit this step.  If your intimidated at the thought of using a pastry bag, just use a zip top storage or freezer bag instead - snip the corner and squeeze.

I’ve used Rose’s strawberry puree (in the Cake Bible) as a cake filling, it tastes of fresh strawberries and was very well-received by adults and children alike.  It is too thin to use as a filling without additional thickener, use either gelatin or agar, both of which must be heated in a little of the liquid until dissolved.  The conserve, already mentioned, is also good. like a more intense, less sweet jam. 

I second the motion for a buttercream dam, it’s not hard to do and will keep your cake sides from bulging or otherwise ruining the buttercream. 

I did not have any bleeding of the puree into the cake at all, having used gelatin to thicken it.

I am so glad Patrincia and Julie gave their input on strawberry filling options—excellent suggestions.

You could also use Pomona’s Universal Pectin (available at Whole Foods Market) to thicken the conserve. Just don’t go overboard with it, or you’ll end up with a very bouncy (as in rubber ball) filling.

Thank you all for so many great suggestions! 
  I’m sorry for not responding sooner, but I didn’t get any emails, after the first one, that any post had been made.  What a jackpot I hit when i decided to check back today anyway, “just in case”!  Fantastic! 
 
  When three of you recommend something, I figure it’s the road to success!  I think I’ll be able to negotiate the buttercream dam.  The deliciousness of the strawberry filling has trumped the unfavorable presence of buttercream between the layers.    Plus, it doesn’t seem as though there needs to be SO much.  I’m guessing a 1” diameter ring at the edge should do it. (?)
 
  I’m glad to know that the strawberry puree mixed with mousseline is as successful as I suspected it to be.  My inexpert guess was that this would be great; nice to get expert confirmation. 
 
  I’m also happy to know I could use a thickener on the puree.  Again, my first thought was to thicken the puree to make the filling, but second I guessed myself.  Rose’s books are always so thorough, I thought that if it yielded a good result, it would be in there.  Good to know that a little fiddling can be done.  ( I often try out variations on breads, but never on the cakes, for some reason.)
 
    I can’t wait to try out some of these ideas!  Thank you again, ladies. 
                                            Melanie

Do you all think these ideas would also work with raspberry?

elbee,
    I think so.  I don’t see any reason why they wouldn’t.  Sounds delicious.  (Raspberry is actually my preference, but the strawberry was a request).  Maybe I’ll do raspberry filling for my own birthday cake, next month!

Raspberries have a lot of seeds, so you may need to strain your puree or put it through a food mill. (I used a food mill the last time I made black raspberry jam.)

I think a home-made jam is a great idea for a filling. When I make jam, I usually start with frozen fruit. I thaw it, drain it, and reduce the juice. Add the juice back in, and if necessary, puree and strain. Then I add sugar to taste, maybe a bit of lemon juice if needed, perhaps a pinch of salt. Put into a large measuring cup.

Now, get yourself some no-sugar-needed pectin. I’ve used several brands—Pomona’s has fewer ingredients with long, chemical-sounding names, but it tends to set up rather firm. Ball and Sure-Gel also make this type of pectin. Don’t get the “1/3 less sugar” type of pectin—it still needs a LOT of sugar to set up. With the no-sugar pectin you can add exactly as much sugar as you like.

Consult the recipe insert from the package of pectin. Usually they give you a recipe for about 4 cups of fruit puree. Adjust as needed for the amount of fruit you have. I usually start with less pectin, maybe 3/4 as much, as I like softer jams. Add acccording to the directions in the package. You can test the set by putting a spoonful onto a plate or small cup and chilling it. If it’s runny, add a little more pectin. If it is thick and rubbery, thin it down with water or fruit juice.

You can also make a lovely home-made jelly using frozen fruit juice concentrate. I usually thin it with a little water, one can instead of the 3 cans you’d usually use. Measure, add sugar and other flavorings to suit, heat, and add pectin. It makes a lovely clear filling or glaze with so much more flavor than those awful clear jels the supermarket bakeries use!

Hello All,
  Just wanted to pop over and thank you all again for the great advice.  Yesterday was the birthday and the cake was exactly what he wanted!  Since I am still a novice I, of course, thought a million things went wrong.  But my husband was delighted with it.  Isn’t that the goal? 
  I ended up using white velvet butter cake, n-c buttercream for the frosting and dam, and strawberry sauce (puree + sugar) with gelatin for the filling.  Delicious.

  Thanks again, Melanie