Preheat oven to 350°F (175°C). Grease a half sheet pan (18×13 inches).

Roll out softened pie crusts stacked together into a rectangle slightly larger than the baking pan. Fit into pan, pressing into corners and trimming excess. Crimp edges.

Line crust with parchment and fill with pie weights or dried beans. Bake 15–17 minutes until golden. Cool completely.

Melt chocolate in microwave in 30-second intervals, stirring until smooth. Let cool slightly.

In a saucepan, whisk eggs and granulated sugar. Cook over low heat, stirring constantly, until sugar dissolves and mixture coats a spoon, about 5 minutes.

Remove from heat and stir in melted chocolate and vanilla. Let cool to warm, stirring occasionally.

Beat softened butter until fluffy, 2–3 minutes. Gradually add chocolate mixture, beating on high until light and fluffy, about 5 minutes.

In a separate bowl, beat heavy cream until thickened. Add powdered sugar and beat until stiff peaks form.

Fold 1½ cups of whipped cream into chocolate filling to lighten it. Reserve remaining whipped cream for topping.

Spread chocolate filling evenly into cooled crust. Chill 1–2 hours until set.

Top chilled pie with remaining whipped cream. Garnish with chocolate shavings or curls if desired.

Slice into squares and serve. Optionally pair with fresh berries.