Quick Fix

• To thicken pastry cream that's already been prepared and cooled, simply add a bit more starch. Combine cornstarch with cold milk or water to make a slurry. Heat the pastry cream to simmering and stir in the slurry. Bring the mixture almost to a boil, whisking constantly, until the pastry cream thickens.

Select a Starch

• The basic technique for making pastry cream is always the same, but the ingredients may vary slightly. For a thicker pastry cream, use a combination of flour and cornstarch when you initially make the pastry cream, rather than just one of these ingredients. For every 1 1/2 cups of milk, add about 1/4 cup cornstarch and 1 tablespoon of flour. Adding another egg yolk also thickens a thin pastry cream.

Full-Fat Dairy

• The type of dairy product you use plays a role in how thick pastry cream becomes. Most recipes call for whole milk. If you use non-fat or low-fat milk, you'll end up with a thin pastry cream that lacks richness. Stick with whole milk, half and half, or even cream for a thick, luxurious pastry cream.

Stir and Simmer

• Cornstarch and flour thickeners work efficiently when combined with egg yolks, but you must cook the mixture thoroughly. If you don't, the amylase enzymes found in egg yolks will break down the thickener as the pastry cream cools, resulting in a watery mess. Even if the pastry cream seems thick, continue to cook it for one to two minutes after it begins simmering. Whisk it constantly so it doesn't burn. This extra cooking time denatures the amylase enzymes, rendering them inactive.