Hattie's cake

Combine a 15 oz box of yellow cake mix, a six-ounce box of instant chocolate pudding powder, three eggs, an 8 oz tub of sour cream, 3/4 cup water, 2/3 cup vegetable oil and 1 tsp vanilla; beat until smooth.

Mix in a cup of chocolate chips and pour into a bundt pan sprayed with flour-containing non-stick spray.

Bake at 350F for 50 to 55 minutes, until the edges brown and pull away and a knife or skewer to the centre comes out clean.

Cool a few minutes, then turn out onto a plate.

To see the water-binding of starch, whisk regular cornstarch into water and bring it to a boil until it gels.

Variation: without pudding powder, replace 10% of the flour in a cake recipe by weight with unflavoured pre-gelatinized starch; more than 10% makes the batter too thin and the cake flat and dense.