Preheat the oven to 330°F (165°C) using static heat. Line a standard loaf pan (9x5-inch/23x13 cm) with parchment paper.

In a microwave-safe bowl, melt half the dark chocolate (3.5 oz/100 grams) with the coconut oil in 20-second intervals, stirring between each, until smooth. Add the eggs one at a time, whisking well after each addition. Stir in the cornstarch, sugar, and salt, and mix until fully combined. Pour the batter into the prepared pan and smooth the top. Bake for 15 to 17 minutes, or until just set in the center. Avoid overbaking. Let cool completely in the pan.

In a blender or food processor, combine the coconut cream and pitted dates. Blend until smooth and creamy. Pour the mixture over the cooled brownie base and spread into an even layer. Freeze overnight until fully set.

Melt the remaining dark chocolate (3.5 oz/100 grams) with the additional coconut oil in short microwave bursts, stirring until smooth. Pour over the frozen coconut layer and spread quickly. Sprinkle with flaky sea salt. Return to the freezer for 30 minutes to set the top.

Remove from the freezer, slice into squares, and serve immediately. Store any leftovers in an airtight container in the freezer for up to two weeks.