* 4 extra-large egg whites, at room temperature
* ²/³ cup(5 oz/155 g) sugar
* 2 tbsp unsweetened cocoa
* 1 cup (8 fl oz/250 ml) heavy (double) cream, whipped with 2 tbsp sugar
* miniature chocolate chips for topping
Top with fresh berries or chocolate shavings in place of the chips, if you like. For a pie with a softer texture, refrigerate for 1 hour after topping with the whipped cream.
1. Position a rack in the middle of an oven and preheat the oven to 300 degrees F. (150 deg C). Generously butter a 10-inch (25 cm) pie plate with 2-inch (5-cm) sides. Dust with flour and tap out any excess.
2. Place the egg whites and sugar in a bowl. Using an electric mixer set on high speed, beat until stiff and glossy but not dry. Reduce the speed to low and beat in the cocoa, mixing only until incorporated.
3. Pour and scrape the batter into the prepared pie plate. Use a rubber spatula to smooth the top, building the rim slightly higher than the center.
4. Bake until the egg whites are light brown and no longer sticky, about 1 hour. Transfer to a wire rack to cool completely. The center will sink as it cools.
5. Just before serving, fill the center with the whipped cream. Sprinkle with miniature chocolate chips.