If you make this recipe at the height of berry season, by all means use fresh fruit. If you're working with off-peak months, however, frozen berries will do just fine. You’ll need two 10-ounce bags to make enough purée. Just whoosh the berries around in a food processor fitted with the metal blade, then pass the purée through a metal sieve in order to remove the seeds. Marshmallows can be made in any sized pan – a 9-by-13-inch pan gives good results. A smaller pan will yield thicker marshmallows, a larger pan will give you thinner ones. Whatever pan you choose, be sure to oil it well or you won’t be able to remove the marshmallows.
Prepare the bloom by placing the gelatin in a small bowl. Add the purée and stir well. The mixture will begin to thicken quickly. Set aside.
Mix all the base ingredients together in a large sauce pan and heat over medium-high heat. Clip a candy thermometer onto the pot and cook until the mixture reaches 250 degrees, about 10 minutes.
Remove the pan from the heat and quickly stir in the bloom. The mixture will foam up, so stir carefully until the bloom is completely incorporated.
Pour the batter into the bowl of an electric mixer fitted with the whisk attachment. Mix on a low speed then gradually increase the speed to medium-high. Let the mixture whip for between 5 and 10 minutes, or until it is fairly stiff but still spreadable. Immediately pour the mixture into a well-oiled pan.
Let the pan sit, uncovered, on the counter overnight. This is called curing and reduces some of the stickiness factor.
Remove the marshmallow slab from the pan and place it on a cutting board. Mix the coating ingredients together and lightly sprinkle some over the uncut marshmallow.
Use a pizza cutter to cut the slab into bite-sized pieces, then toss the pieces with the remaining coating so they will not stick together.
Store the coated marshmallows for several days at room temperature.
4 Tbsp. unflavored gelatin
1¼ cups blackberry purée
Base
½ cup water
2/3 cup blackberry purée
1¼ cup light corn syrup
2 cups sugar
Coating
2 Tbsp. cornstarch
1/3 cup powdered sugar
This article appears in January 2011.