Scoop the peanut butter into the bowl of an electric stand mixer. Add the vanilla extract and salt. Beat to combine. Then turn the mixer on low and slowly add in the powdered sugar and cornstarch. Once combined, scrape the bowl with a spatula, then beat on high for 2-3 minutes to lighten the texture.
Scoop a round mound of peanut butter filling onto each disposable spoon. Try to make each mound smooth and symmetrical by scraping the edge of the spoon on the side of the bowl, but they don’t have to be perfect. Press a mini marshmallow at the base of each mound, right above the handle, as bunny tails. Then press 2 candy corns, pointed ends up, closer to the tip of the spoon, for ears. (See images if needed.)
Place the spoons on a baking sheet and refrigerate for at least 1 hour to firm up the filling and ensure the ears and tails don’t fall off when dipping in chocolate.
When the peanut filling on each spoon is cold and firm, place 7 ounces dark chocolate in the crock of a double boiler. Filling the lower pot with one inch of water, set the crock on top, and set the pot over medium-low heat. Stir the chocolate until melted. Then turn off the heat and add the last 2 ounces of dark chocolate. Stir until all the chocolate has melted. This tempers the chocolate so it does not turn cloudy once dried.
Lay a large piece of wax paper out on the counter. Take 2-4 truffle spoons out of the refrigerator at a time, leaving the rest to chill as you work. Hold one truffle spoon over the pot of chocolate and use another large spoon to shower the truffle in melted chocolate until completely covered. Tap the truffle spoon gently on the edge of the pot to remove extra chocolate.
Set each chocolate-coated bunny spoon on the wax paper. Quickly attach two eyes and a nose in front of the ears, before the chocolate hardens. Repeat with the rest of the spoons.
Once completely dry, wrap each bunny truffle spoon in a small cellophane bag and tie with ribbon. Leave at room temperature for up to 1 week.