Preheat the oven to 350°F (175°C). Spread 1 cup of shredded coconut evenly onto a rimmed baking sheet. Toast in the oven for approximately 10 minutes, stirring frequently, until the coconut turns a uniform golden brown. Remove from oven and allow to cool completely.

Lightly grease a 9×13-inch baking pan with butter. Line the pan with parchment paper, ensuring the paper extends over the two shorter sides to create handles for easy removal. Grease the parchment paper as well and set the pan aside.

In a large saucepan set over low heat, melt the butter. Add the marshmallows and stir continuously until they are fully melted and smooth, which should take about 6 minutes.

Stir in ½ cup of shredded sweetened coconut along with the coconut extract. Mix until well combined. Remove the saucepan from heat.

Immediately stir in the Rice Krispies cereal. Mix thoroughly to ensure the cereal is evenly coated with the marshmallow mixture.

Transfer the mixture to the prepared baking pan. Using a piece of wax paper or a spatula, press the mixture firmly and evenly into the pan.

Sprinkle the toasted coconut evenly over the top of the treats and press lightly to ensure it adheres.

Place the bittersweet chocolate chips in a microwave-safe bowl. Heat on high for 30 seconds, then stir. Continue heating in 15-second intervals, stirring well between each, until the chocolate is fully melted. Drizzle the melted chocolate over the bars.

Allow the bars to cool at room temperature until the chocolate has hardened. Once cooled, lift the bars out of the pan using the parchment handles and cut into squares for serving.