Preheat the oven to 350 degrees. Melt the coconut oil and the chocolate over very low, gentle heat. Whisk the chocolate mixture in a bowl with palm sugar. Whisk in the eggs until the mixture thickens, about 30 seconds. Add the espresso. Stir in the flour and salt until just combined. Pour into a 9-inch square baking dish that has been sprayed with non-stick spray and bake for 25 minutes. Serve with vanilla ice cream or gelato.