Watermelon Marshmallows

Name: Watermelon Marshmallows
Cuisine: American
Ingredients: Nonstick cooking spray; 240 milliliters water (about 1 cup, divided); 20 grams powdered gelatin (2 tablespoons; about 2 1/2-3 packets); 400 grams granulated sugar (2 cups); 200 grams corn syrup or liquid glucose (1/2 cup); 1/4 teaspoon fine sea salt; 1 teaspoon watermelon flavoring, or to taste; 5-6 drops pink gel food coloring; 90 grams miniature chocolate chips (1/2 cup), plus more for decorating; 135 grams green candy melts (3/4 cup); 1-2 teaspoons vegetable oil, or more as needed to adjust consistency; 50 grams cornstarch (1/3 cup); 50 grams confectioner’s sugar (1/3 cup)