In a small bowl mix together the Corn Starch (2 tablespoon) and All-Purpose Flour (2 tablespoon).
Bring Milk (17 fluid ounce) and Vanilla Extract (1 teaspoon) to a boil. Once it boils, turn off the heat.
Beat Egg (4) with Granulated Sugar (2.5 ounce) until pale yellow. Add flour mixture and continue stirring.
To temper the egg yolk mixture, add about 1/2 cup of the milk and mix quickly. Add the egg mixture to the milk. Cook over medium heat stirring frequently until it thickens.
Transfer to a clean bowl and set it over ice bath. Cover with plastic wrap so that it touches the cream and refrigerate it.
Whip Heavy Cream (1/2 cup) until it forms stiff peaks. Don’t overbeat it. Add whipped cream to the pastry cream and mix until well combined.