Scrumptious science

Consider these directions for the preparation of an English custard sauce:

“… the custard … will be very thick and go blop, blop, but you must be sure to get this entire mixture to a good boil to kill enzymes in the yolks or these enzymes will destroy the starch and the custard will … turn to soup while standing.”

Odd as they are, these instructions signal something wonderful: Shirley’s back.

After 10 years, Atlanta cooking teacher and food scientist Shirley O. Corriher has finally finished the follow-up to her groundbreaking “Cookwise” —- a book filled with folksy taste pleasures, oddly subversive recipes and applied scientific reason in its purest form. It was an instant classic for both professionals and home cooks.

Corriher, who was a research chemist at Vanderbilt University, first made her name in the food world as a consultant to cookbook authors, such as Julia Child, and food manufacturers, such as Pillsbury. For years, she has been the first person the nation’s food writers call when a recipe misbehaves. Her chemistry lessons, delivered with a reassuring Southern voice, have kept many a recipe developer off the ledge.

Corriher’s new book —- “Bakewise: The Hows and Whys of Successful Baking” (Scribner, $40) —- takes the same inimitable approach in its joyous deconstruction of more than 200 dessert recipes. It looks bound to be another keeper, and I’ll tell you my first round of testing recipes from it yielded excellent results.

Corriher pays as much attention to homey American treats as to French pastry. She’ll convince you to prepare a crisp, refrigerator-safe crust with Wondra flour and butter-flavored Crisco (transfats be damned), then send you off in search of hazelnuts for making your own frangipane paste for a pear tart.

But the hallmark of Corriher’s approach is that she starts with the desired results, then thinks her way back through the process and never takes conventional wisdom for granted.

That pie crust, for instance, contains a bit of both powdered milk and corn syrup. Why?

“Well,” explains the ever-bubbly Corriher on the phone, “it’s for browning. The Maillard reaction needs three things to occur. One is a reducing sugar, which is a sugar with a certain kind of tail end and that’s all you really need to know, and a protein, and a situation that’s not real acidic.”

Many a baker wouldn’t know from a Maillard reaction, but the bottom line is this crust is dark, crisp and full of flavor —- unlike some wan shortening crusts. It also keeps its integrity for days in the fridge (a thin layer of bread crumbs on the bottom helps) and thus is perfect for the ultracreamy deep-dish pumpkin pie Corriher makes in it.

Corriher has lived in Atlanta since the 1950s, when she cooked meals nightly for 30 boys at a small private school. She credits this experience as well as her chemistry degree to her unique approach. As a Southerner, she has thought long and hard about the delight of a truly moist layer cake and offers three recipes. I tried the most unusual, which begins with sugar dissolved in hot water and ends with whipped cream folded into the batter. The cake baked up 2 inches high and perfectly level. When I cut the cake into three horizontal layers it had just the right mix of resilience and tenderness.

So fine was this cake, that I turned it into Corriher’s Boston Cream Pie —- the whole covered in a gloss of chocolate ganache. Unlike other recipes that involve boiling cream poured into chocolate, this ganache involved a measuring cup, a microwave and a touch of corn syrup to give it a velvety texture.

All of Corriher’s recipes come with a fun little lesson plan, in which she explains the chemical principles at work.

When you get cooking, you’re also getting into a chemistry experiment, a feeling my inner nerd found most appealing. For instance, the chocolate crinkle cookies I made had gooey soft centers thanks to the way oil greased the flour proteins within. They were also gorgeous, with snow-white powdered sugar crackles revealing a dark chocolate heart. How does Corriher keep the colors so distinct?

“Unlike other crinkle cookies, you roll these ones in granulated sugar before rolling them in powdered sugar,” she says in her animated way. (Shirley Corriher is more animated than most Disney characters.) “The cookies don’t absorb any of the powdered sugar!”

That is Shirley Corriher’s greatest lesson. Sometimes the best science teacher is common sense.