Line a baking sheet with a silicone mat, parchment paper or foil and spray lightly with nonstick cooking spray.
Put the chocolate in a heat-safe glass bowl and set over a pot filled with an inch of water. Place the pot over medium-low heat and gently cook the chocolate, stirring occasionally, until melted. Add the sea salt.
Mix the granola, graham cereal and toffee bits in a shallow dish.
Using two forks, dip the marshmallow rounds in the melted chocolate, letting excess chocolate drip off. Roll in the granola mixture, then transfer to the prepared baking sheet. Refrigerate on the baking sheet until the chocolate is set, 10 to 15 minutes. Store in an airtight container if not using immediately.