Help! What went wrong with my recipe?

Everyone does it sometime. You're following a recipe to the letter. And yet ... something goes wrong. The fudge fails. The roast is tough. The sauce breaks. "What did I do?" you moan — and thus begins the search for the cause of the mess.

We asked readers, to share their tales of woe. Then we checked in with culinary experts and our own test kitchen staff to find the source of their problems and how they can fix them in the future.

Pay attention, now. You never know when someone else's problem will become your own. The main thing, though, is to keep cooking.

Case No. 1: The crying game

Q: I just love banana and lemon cream pies. I have made these successfully but, in the last few tries, they became watery. Is there a trick for adding the cornstarch so as to not develop a watery end product?

— Maryann Kull, Crystal Lake, Ill.

A: Cream-pie fillings "rely primarily on the coagulation of the proteins in the eggs to create (firmness)," according to The Prepared Pantry Web site (preparedpantry.com). These pies usually rely on egg yolks because they are high in protein as well as fat, which is "needed to create the rich, smooth texture that we expect in custards," says Dennis Weaver, president of The Prepared Pantry.

Cornstarch is added as a thickener and binder that helps prevent pies from weeping because, Weaver explained, it "sops up" any excess moisture in the filling.

You need to cook the filling long enough so the mixture coagulates (that happens at 160 degrees), but if you cook it too long and don't stir the mixture enough (stirring keeps the temperature down), you'll overcook the custard: Overcooking breaks down those all-important proteins, and that's when the weeping starts. "Joy of Cooking" recommends that custards be cooked over medium heat — not high or even medium-high — to help prevent overcooking. On the other hand, he explained, once the filling begins to cool, take it easy with the spoon: If a custard is overstirred, especially as it cools, he said, the cornstarch granules deflate and lose their ability to thicken.

Some recipes temper the yolks by first stirring some hot filling into them, then pouring the yolks-and-filling combo back into the saucepan. But we found that the streamlined recipe in "Joy" was much easier to execute, though it required more stirring and whisking as the custard cooked. Our lemon cream pie turned out creamy and firm, with no seepage.

• LEMON CREAM PIE

Preparation time: 35 minutes

Cooking time: 15 minutes

Chilling time: Three hours

Yield: Eight servings

Vanilla wafer crumb crust:

11⁄4 cups vanilla wafer crumbs, about 35 cookies

1⁄2 stick ( 1⁄4 cup) butter, melted

1 tablespoon sugar

Filling:

3⁄4 cup sugar

1⁄3 cup cornstarch

1⁄4 teaspoon salt

31⁄2 cups milk

5 egg yolks

2 tablespoons unsalted butter, cut into small pieces

2 teaspoons minced lemon zest

1⁄4 cup fresh lemon juice

1⁄2 teaspoon vanilla

Whipped cream, optional

Putting it together

1. For the crust, heat oven to 375 degrees. Mix the wafer crumbs, melted butter and sugar with a fork in a 9-inch pie pan until crumbs are evenly moistened. Press mixture firmly onto bottom and sides of pan, making a small rim. Bake 10 minutes; set aside.

2. For filling, whisk the sugar, cornstarch and salt in a heavy saucepan; gradually whisk in the milk. Whisk in the egg yolks until no yellow streaks remain.

3. Heat mixture just to a simmer over medium heat, stirring constantly. Remove pan from heat; whisk until smooth, being sure to scrape sides of pan. Return pan to medium heat; cook, whisking constantly, until thickened, about one minute.

4. Remove saucepan from heat; whisk in the butter, lemon zest, lemon juice and vanilla, whisking just until the butter melts. Spoon the filling into the prepared crust; press plastic wrap directly on the surface. Refrigerate at least three hours or overnight. Serve with whipped cream, if desired.

Case No. 2: Foiled by fudge

Q: For many years, I made (a fudge recipe) and it always turned out fantastic. However, one year I went to make the fudge, and all of the fat separated out of the mixture as I was stirring it and the fudge turned out rock hard instead of soft and creamy. I tried it at least two more times, but they failed. Eventually I just gave up. The only thing I can think of that has changed was that I started using a premium chocolate as opposed to the more commonly available Hershey's and Bakers.

— Barb Zaniolo, Flossmoor, Ill.

Q: I have a 15-year-old fudge recipe. But for the last three years, the fudge will not set up. It's soft and can't be cut well. (The recipe) does not require a candy thermometer, but I tried that. No use. One ingredient, the evaporated milk, originally came in a 14-ounce can and now is 12 ounces, so we (tried adding) the extra 2 ounces; no good. Please help.

— Mary Stathopoulos, Schaumburg, Ill.

A: Though each of your fudge problems are different, the common denominator is a ruined texture.

"The smooth and creamy texture of fudge has to do with how much water is left in the mixture after boiling, and the resulting sugar syrup's concentration," noted Sarah Phillips, founder and CEO of baking911.com.

"If the mixture was boiled beyond the required temperature, the sugar syrup will become especially concentrated, the fudge will be hard, crumbly and dull in appearance. Conversely, if the fudge has been undercooked, or it is humid and absorbs moisture from the air, it will become soft and many times, runny."

A broken candy thermometer might be to blame, Phillips said. These delicate instruments break easily. To see if yours works, put it in a pan of boiling water. It should read 212 degrees in about 10 minutes.

In the first recipe, the fudge might be boiling for too long: "If a fudge recipe gets too hot, the cocoa butter and other fats get squeezed out of suspension and will separate out." Try reducing the amount of boiling time the recipe calls for.

For the second recipe, which did not require a candy thermometer, try boiling the fudge a minute or two longer to reduce the liquid in the candy.

Variations in how ingredients are manufactured also can affect a recipe, Phillips said. The way a chocolate was formulated 15 years ago might have changed, or the 12-ounce bag of semi-sweet chocolate bits that you used to buy is now 11 ounces.

Phillips also suggested that you both use "pure cane sugar," which is labeled on brands such as Domino and C&H. C&H's Web site notes that pure cane sugar has a lower melting point than other types of granulated sugar (often made from beets), and that difference may factor into your final result.

Case No. 3: Mac 'n' cheese blob

Q: I found a great recipe for macaroni and cheese from scratch. I followed the recipe exactly. After I added the Cheddar cheese, I ended up with nothing but a big glob of cheese that started looking strangely enough like orange plastic in the bottom of my pot. The longer I cooked it, the worse it got. The stuff never melted into the creamy sauce I was expecting. I'm hoping you can help me.

— Mary Jane Butkus, Chicago

A: You need flour in that baked macaroni and cheese, explained Corrine Kozlak, the Good Eating food stylist/tester who tried your recipe. Simply melt the butter, stir in about 2 tablespoons of flour, then add the milk. Whisk until the milk comes to a low boil. As you slowly add the cheese, let each handful melt before adding the next one. And regulate the heat so the sauce is just barely bubbling, which helps the melding take place.

• THREE-CHEESE MAC AND CHEESE

Preparation time: 15 minutes

Cooking time: 55 minutes

Yield: Eight servings

2 cups uncooked elbow macaroni

2 tablespoons each: butter, flour

2 cups milk

1⁄2 teaspoon salt

Freshly ground pepper

2 cups shredded sharp Cheddar cheese

1⁄2 cup shredded Colby cheese

1 cup shredded Monterey Jack cheese

1 cup bread crumbs

Putting it together

1. Heat the oven to 350 degrees. Cook the macaroni according to package directions; drain.

2. Meanwhile, melt the butter in a large saucepan over medium heat; whisk in the flour. Cook, whisking, two minutes; gradually whisk in the milk. Add the salt and pepper to taste. Lower heat to a simmer. Cook, stirring occasionally, five minutes. Stir in the Cheddar and Colby cheeses, a handful at a time; cook, stirring, until melted and smooth, about 3 minutes.

3. Stir in the cooked macaroni; pour half of the mixture into a buttered 11⁄2 -quart baking dish. Sprinkle half of the Monterey Jack cheese over the macaroni mixture; add remaining macaroni mixture. Top with remaining cheese and the bread crumbs. Bake until bubbly and light brown on top, about 30 minutes.