The souffles can made in one large bowl (and then scooped out into servings), layered into parfait glasses with raspberries, or spooned into 4 4-oz ramekins. If you choose to serve them in ramekins (as seen the photos), you will need to make foil collars for the ramekins. Cut off four pieces of foil, each long enough to fit around the edge of the ramekins and about 9 inches wide. Then fold the foil over twice so it is 3 inches wide. Circle the ramekin and tape the foil in place. Spray or rub the inside of the foil collar with vegetable oil.
In a small bowl, mix together the lemon juice and lemon zest. Sprinkle the gelatin over the lemon juice and set aside.
Make an ice water bath in a container large enough to fit your medium bowl.
Heat the milk and 1/4 cup of the sugar in a medium saucepan over medium-low heat until the milk is hot and beginning to steam and the sugar is dissolved, about 5 minutes. While you are waiting for the milk, whisk together the egg yolks, 2 tbsp of the sugar, and the cornstarch in a medium bowl. Keep whisking until the mixture is light yellow and thick, about 2 minutes. Once the milk is done, gradually pour the milk into the yolks while whisking the yolks constantly. Add about half the milk this way. Then begin pouring and whisking the milk and yolk mixture into the saucepan with the rest of the milk. Continue whisking as you heat the custard until it thickens to coat a spoon and reaches 185F on a thermometer, 5-6 minutes. Strain the mixture back into the medium bowl and then stir in the lemon juice and gelatin. Place the custard into the ice bath to cool to about 95F.
In the same mixing bowl, add the heavy cream and vanilla. Beat the heavy cream on medium high until it holds soft peaks. Fold the cream into the custard until fully combined. Spoon the souffle mixture into the prepared ramekins, or parfait glasses, or large serving dish. Allow to chill for at least 2 hours, up to 8 hours. Top with berries and confectioners' sugar and serve.