Heat the oven to 325 degrees. To make the tart easier to remove later, crumple a (10-inch) sheet of parchment paper, then spread flat and use it to line the bottom and sides of the pan.

Spread the coconut flakes on a rimmed baking sheet and bake, stirring once halfway through, until golden, about 10 minutes. Cool completely on the pan.

Melt the dark chocolate in a large heatproof bowl set over a saucepan of simmering water, stirring occasionally, or in the microwave in 10-second bursts, stirring between each increment. Slightly crush the coconut flakes (to be able to press them into the tart pan without leaving gaps), then stir them into the chocolate, followed by the salt. Mix well until evenly coated.

Press the chocolate mixture into the bottom and up the sides of the prepared pan, making sure there are no holes. There should be a fairly robust (½-inch-thick) crust around the edges. Chill in the fridge or freezer until firm, 20 to 30 minutes.

Meanwhile, make the crémeux: Steep the teabags in the boiling water for about 20 minutes, until the tea is around room temperature. While the tea steeps, place the finely chopped milk chocolate in a heatproof bowl.

Whisk the egg and cornstarch in a medium saucepan until smooth, paying special attention to the edges of the pan. Whisk in the heavy cream.

Squeeze the teabags when removing them from the water. Whisk the strong Earl Grey infusion into the saucepan.

Bring the tea mixture to a boil over medium heat, whisking constantly to prevent clumping, until thickened, 2 to 4 minutes. Turn the heat to low and whisk for about 30 seconds more, then turn off the heat and whisk in the butter.

Pour the tea mixture over the chocolate. Let stand for about 30 seconds, then whisk until smooth. Finally, whisk in the salt. Taste and add more salt if you’d like. Pour the crémeux into the chilled crust, using a spatula or spoon to level out the top. Transfer to the fridge and chill for at least 4 hours (though preferably overnight), or for up to 2 days. Once the filling is set, cover the tart with plastic wrap or an overturned bowl to prevent the crémeux from absorbing other scents in the fridge.

To finish: Remove the chilled tart from the fridge and remove the tart tin or slide the tart out of the pie plate using the parchment. Place the tart on a serving plate, discarding the parchment. Finely grate dark chocolate all over the top. Sprinkle with the cornflowers, if using. Let stand at room temperature for at least 30 minutes for a softer texture. Slice with a sharp knife and serve.