01 - Place the peeled and sliced bananas into a blender. Add 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 chopped dark chocolate and coconut oil in a microwave-safe bowl. Microwave in 20-second intervals, stirring between each, until fully melted and smooth. Alternatively, melt over a double boiler set over simmering water, stirring constantly.
03 - Pour half of the banana-yogurt mixture into the popsicle molds, filling each cavity approximately halfway. Drizzle a generous layer of the melted chocolate over the banana base in each mold. Use a skewer or the tip of a small knife to gently swirl the chocolate through the banana mixture, creating a marbled effect.
04 - Divide the remaining banana mixture evenly among the molds, filling them to just below the rim. Drizzle with more melted chocolate and swirl again to your preference.
05 - Insert a popsicle stick into the center of each mold, pressing gently until secure. If desired, sprinkle the tops with chopped roasted nuts or mini chocolate chips, pressing lightly so they adhere.
06 - Transfer the filled molds to the freezer and freeze for a minimum of 4 hours, or until the popsicles are completely firm and set through to the center.
07 - To release each popsicle, hold the mold under warm running water for 10 to 15 seconds, then gently pull the stick upward. Serve immediately.