I've been low-carbing for years now. Most of the time, I don't give much thought to the recipe tweaking and ingredient substitution it takes to convert a standard recipe into something that won't spike my insulin and make me grumpy.

But sometimes, those thoughtless substitutions are a little too thoughtless, and I'm left with a disaster on my hands. Just last week I whipped up a batch of my acclaimed lemon squares, tweaking along the way. I was really looking forward to the buttery shortbread crust and the tart lemon custard topping. What I got instead was crumbly sawdust held together by a thin strip of chewy lemony stuff.

Where did I go wrong? The answer was obvious in hindsight: the sugar substitute.

It may seem odd, but sugar, in baking, is a liquid. If you're baking something where sugar is a minor ingredient, you can pick and choose among the available sugar substitutes with only minor changes in texture in the finished product. But if the sugar, by weight, is one of the major ingredients, substitute carefully, taking into account the volume that the sugar makes up in the finished recipe.

In the case of the desert-lemon-squares, I had replaced 2 cups of sugar with 3 teaspoons of concentrated liquid Splenda sweetener*. In my zeal to keep the carbs low, I hadn't given a thought to how removing all that liquid (the sugar) would affect the outcome; the only other major ingredient in the topping was eggs. I should have used pourable Splenda, or erythritol, or a sugar-free syrup; or even a combination of two or three of them. As it was, putting my tweaked ingredients into the oven for 20 minutes didn't produce anything except disappointment — and lemon-flavored rubber.

But wait! This story does have a happy ending. Do you think this is the first time I've been left with something close to inedible? While I'm touched by your confidence in me, I have to confess that, even after nearly 6 years, this is still a trial-and-error process. Some things just don't work the way I think they might, but I've managed to rescue any number of baked-good "attempts" using what I think of as The Bread Pudding Method (BPM).

When I was a kid, my mom used to save the ends of the loaves of bread — we wouldn't use them for sandwiches or toast, being picky that way — and freeze them until she had "enough". Then she would roughly rip up the bread into a buttered casserole dish (about two-thirds full), stir in a couple of beaten eggs, some sugar, and some milk (everything should be nice and soupy), maybe tossing in some raisins as well. A quick grating of nutmeg topped it off, and then she'd bake the whole thing (325 degrees) until it was set (40 minutes to an hour, depending on the size of your casserole).

You can imagine that Mom's bread pudding was the ultimate comfort food treat, suitable for breakfast, snack, or dessert. You may also be wondering what this has to do with the failed lemon squares.

Think of the BPM as an insurance policy for baking with expensive LC ingredients. It's difficult to just toss something out when the texture is all wrong, or it's too sweet, or not sweet enough. All of these conditions can be corrected using the BPM, because you can add moisture or sweeteners, or balance out a too-sweet something by incorporating it into a pudding to which you add little or no additional sweeteners.

Some things to keep in mind:

• The ingredients you add will add carbs, too; but since you're also increasing the volume of your final product, you will most likely get more servings, too.
  
  

• If you don't like custards or regular bread pudding, don't bother with an "attempted save" unless there's someone else around who does. There's no point in throwing good ingredients after bad if you won't enjoy the outcome.
  
  

• You probably won't end up with something that's fit for company, but I'm betting it will make a nice snack or breakfast treat.
  
  

• There is no recipe, you'll just have to wing it. Don't leave out the eggs; you need the protein to bind the custard. The type and amount of sweetener you add is completely up to you. Do make sure you have enough liquid to make everything nice and squishy before you put it in the oven.