Chocolate-Dipped Crème de Menthe Marshmallows

INGREDIENTS

• About 1 cup confectioners' sugar for coating pan and marshmallows
• 3 tablespoons crème de menthe
• 1/4 teaspoon (about 25 drops) green food coloring (preferably organic), or more as desired
• About 6 ounces bittersweet chocolate, finely chopped
• Pastry brush; 1 (9-inch) square baking pan; small, fine-mesh sieve; 4 1/2-quart or larger stand mixer fitted with the whisk attachment; candy thermometer; wire rack set over a baking sheet
• 1 1/2 cups granulated sugar
• 1/4 teaspoon salt
• 1 cup light corn syrup
• 1 1/2 tablespoons vegetable shortening, preferably trans-fat-free
• 1 teaspoon peppermint extract
• Vegetable oil for brushing pan
• 3 (1/4-ounce) envelopes powdered unflavored gelatin