Preparation

Make the sorbet

In a small saucepan, combine the sugar and orange juice, and simmer over medium-high heat, whisking continuously, until the sugar is disolved, 2 to 3 minutes. Transfer to a small bowl and refrigerate until chilled, about 1 hour.

In a high-power blender, combine the passionfruit pulp, mango, and chilled orange juice mixture. Blend on high until smooth and creamy, then gently fold in the chocolate just until combined. (Don’t overmix, otherwise it will muddy the bright orange color of the sorbet.) Transfer to a freezer container, and freeze at least 6 hours or overnight.

Make the cookies

Preheat the oven to 350°F. Butter a 13×9-inch cake pan, and line the bottom with parchment paper.

In a large bowl, beat the butter, sugars, vanilla, and salt with an electric mixer on medium speed until fluffy. Beat in the egg until smooth.

In a small bowl, whisk together the flour, cocoa powder, and baking soda, and add it to the butter mixture. Beat on low speed until combined. Using a spoon, dollop the batter across the prepared cake pan, and smooth it out in a thin even layer, taking it all the way to the edges of the pan. (You may need to dip the back of your spoon in water to help spread evenly.)

Bake until set, 16 to 18 minutes, rotating the pan halfway through. Transfer the pan to a wire rack, let cool completely, then place in the refrigerator to chill overnight.

Assemble the sandwich bars

Remove the cookie and parchment from the pan. Line the pan with plastic wrap. Using a ruler, cut the cookie in half crosswise. Place one cookie half, upside down, in one end of the pan.

Remove the sorbet from the freezer, and scoop it into the center of the upside-down cookie, leaving about ½ inch along the edges. Top with the other cookie half, pressing down gently to help spread the sorbet to the edges. Fold up the plastic wrap to keep the sorbet in place, and freeze for at least 4 hours or until completely hardened.

In a small saucepan, heat the coconut manna over medium-high heat until just melted. Remove from the heat and let cool until room temperature but still pourable.

Remove the sandwiched sorbet from the freezer, cut into six 2×4-inch sandwiches, and insert a wooden pop stick into each. Place on a parchment-lined tray, spoon over the melted, cooled coconut manna, and sprinkle with the coconut. Immediately freeze at least 20 minutes until the coconut manna hardens into a thin shell. Serve once hardened, or wrap individually and freeze until ready to serve.