Place a bowl in the freezer for 15 minutes. Pour the milk into the bowl, add the sugar and whisk on high speed until stiff peaks form.
Melt the chocolate and the oil in a double boiler. Let it cool down completely, then add the coconut whipped cream and whisk gently until combined.
Spread the filling over the crust and let it sit for at least 4 hours in the fridge.
Before serving top the tart with a little sea salt flakes (without exaggerating!)