Make the Pudding

1. Add the egg yolks to a small bowl and lightly beat them. Set aside.
2. Add sugar, cornstarch, heavy whipping cream and champagne to a large saucepan and mix until smooth. Cook, stirring continuously, over medium heat until mixture just begins to thicken and simmer. Be careful not to boil it.
3. Pour a little bit of the milk mixture (about 1/3 of the mixture) in a slow stream into the egg yolks, while whisking together continuously so that the eggs don’t scramble. Add the egg mixture to milk mixture, putting it all back in the pan. This process ensures that you don’t cook the egg yolks too quickly and get scrambled eggs.
4. Place the pan back on the heat and bring to a light boil. You should see large bubbles slowly popping on top. Allow to boil for 1 minute, stirring continuously. Don’t boil for too long, or you can overcook it and it’ll actually break down, rather than get thicker.
5. Remove from heat and add the butter and vanilla extract. Stir until smooth, then pour into a bowl. If it seems lumpy, you can strain it to remove any lumps. Cover with clear wrap pressed against the top so that it doesn’t get a film on top and set in the fridge to cool completely, 1-2 hours.

Make the Whipped Cream

1. Add the heavy whipping cream, champagne and powdered sugar to a large mixer bowl and whip on high speed until stiff peaks form. Set aside.

Assemble the Trifles

1. Put the additional 1/2 cup of champagne in a small bowl.
2. Make the bottom layer of the trifle by dipping vanilla wafer cookies into the champagne and then breaking them up. Place them into the bottom of each of the four serving glasses*. Sprinkle some additional champagne over the cookies, if desired. I used about 2-3 cookies per layer (4-5 cookies per cup). 
3. Top the champagne-dipped cookie layer with about 2 tablespoons of champagne pudding.
4. Top the pudding with 1 1/2 – 2 tablespoons chopped strawberries.
5. Repeat another set of layers starting with champagne-dipped cookies (broken up and drizzled with additional champagne, if desired), pudding and then more chopped strawberries.
6. Top the trifles with a swirl of whipped cream, some sprinkles and a strawberry, if desired.
7. Refrigerate for about 2 hours before serving. Trifles taste best when eaten within 1-2 days.