1. Mix sugar and flour in a saucepan away from the heat. Whisk in eggs until incorporated. 
2. Heat the mixture over medium-low for about 1 minute. Gradually pour in hot milk and vanilla, adding a little at a time and whisking constantly until sauce has thickened, about 5 minutes. Remove from heat. 
3. Cover with plastic wrap and refrigerate until completely cold, for at least 3 hours. 
4. Use the pastry cream as a pie filling or in trifle, or serve with fresh fruit. 

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