In a medium bowl, whisk together the peanut butter, pumpkin puree, maple syrup, pumpkin pie spice, coconut oil, vanilla extract, and sea salt. Add the rice crisp cereal and stir to combine.
Line a muffin tin with liners. Divide the mixture between the 12 liners (~ 1.5-2 tbsp per cup) and use your fingers to press down firmly. Place in the freezer while you melt the chocolate.
In a small bowl, combine chocolate chips and coconut oil. Melt together by microwaving for 30 second intervals, stirring in between, or heat over the stove in a double boiler.
Remove the muffin tin from the freezer and top each cup with melted chocolate (~ 2 tsp per cup). Use a small spoon to spread out to the edges, or tilt the pan to evenly coat. Place in freezer until firm, about 1.5-2 hours. Once set, sprinkle with flaked sea salt and enjoy!