Ina Garten-Inspired Sweet Potato Casserole

Compiled by Igor Kukolj, Editor. Nobody here has cooked this — how these are made.

Boiled sweet potatoes need a great deal of added sugar. Baked ones need very little, and the reason is not just concentration.

Sweet potatoes contain an amylase enzyme that converts their starch into maltose, and it works in a narrow window between about 60°C and 75°C. Bake them slowly and they spend a long stretch inside that window, and the enzyme turns a substantial part of the starch to sugar. Drop them into boiling water and they race through it in a couple of minutes, so almost no conversion happens — and then some of what sugar there was leaches into the water.

A baked sweet potato is meaningfully sweeter than a boiled one made from the same root. That is not concentration, it is chemistry, and it means this casserole needs half the sugar most recipes call for.

Bake them whole, skin on

Pierced and put straight on the oven shelf at 190°C for an hour. No foil — foil traps steam and effectively boils them. You want the skins slightly collapsed and sugar caramelising out of the pierce holes.

The topping decides which dish this is

Marshmallow makes it a dessert served with turkey. A pecan and brown sugar streusel keeps it recognisably a side. Both are traditional depending on whose family you ask; the streusel below is the one that still tastes like a vegetable.

Do not put sweet potato in a food processor

The cells rupture and release long starch chains, and the mash turns stretchy and gluey in a way that never recovers. A masher or a fork, and stop when it is mostly smooth.

Storing

Assemble without the topping up to two days ahead; add it before baking. Baked, it keeps four days and reheats well at 170°C, covered for the first ten minutes.