Here are a few additional tips to the instructions below and the recipe, which will help your soufflés turn out successfully.
Make sure your tools and equipment are immaculately clean, especially the bowl and whisk you are using. Try to use older egg whites, up to 2 weeks old is great as these perform better, and make sure the whites are at room temperature as well. Mix one-third of the meringue into the pastry cream fairly vigorously, so as to loosen the thick cream before gently folding in the remainder to make sure the aeration is maintained.