01 - Place the peeled and sliced bananas into a blender along with the Greek yogurt, honey or maple syrup, and vanilla extract. Blend on medium speed until the mixture is completely smooth and creamy, scraping down the sides as needed.
02 - Combine the dark chocolate and coconut oil in a microwave-safe bowl. Heat in 20-second intervals, stirring between each, until fully melted and smooth. Alternatively, melt over a double boiler, stirring continuously.
03 - Pour half of the banana mixture into the popsicle molds, filling each one approximately halfway. Drizzle a spoonful of the melted chocolate into each mold, then gently swirl using a skewer or small knife to create a marbled effect.
04 - Divide the remaining banana mixture among the molds, filling them to the top. Drizzle additional melted chocolate over the surface and swirl again to your preference.
05 - Insert a popsicle stick into the center of each mold. If desired, sprinkle the tops with chopped roasted nuts or mini chocolate chips, pressing gently so they adhere to the surface.
06 - Transfer the filled molds to the freezer and chill for at least 4 hours, or until the popsicles are completely firm throughout.
07 - Briefly run the outside of each mold under warm water for 10 to 15 seconds to loosen the popsicle. Gently pull upward on the stick to release. Serve immediately.