Step 1

Crack the eggs into a medium bowl and beat well. Add the sugar and lemon juice and whisk until sugar is mostly dissolved. Set aside.

Step 2

Fill the bottom of a double boiler pan with an inch of water. Bring to a simmer, then turn the heat down to low. Melt the butter in the top of double boiler. Add the egg mixture and cook, stirring constantly, until smooth and thick enough to coat a metal spoon, about 10 minutes. (If you get any bits of cooked egg, pass the mixture through a fine sieve to remove.) Stir in the lemon zest and pour into a shallow bowl. Chill in the refrigerator until cold.

Step 3

Pour the chilled whipping cream into the bowl of an electric mixer and beat until the cream holds firm peaks (when you lift the whisk or beaters out of the bowl, the peak should hold its shape without drooping; if the cream looks grainy, you’ve gone too far and should start over). Be sure the lemon mixture is completely cool; then, using a rubber spatula, gently fold it into the whipped cream.

Step 4

Place a large spoonful of berries into each glass (leave room for 2 layers of berries and 2 layers of cream) and top with a generous dollop of lemon cream. Top with another layer of berries and lemon cream. Cover with plastic wrap and chill until ready to serve. (Parfaits can be assembled up to this point several hours ahead of time.) Right before serving, top each parfait with a shortbread cookie and sprig of fresh mint.

Step 5

Note: Anytime a recipe calls for lemon juice and lemon zest, be sure to zest the lemon before squeezing out the juice.