You'll be making two consecutive batches of marshmallow for these, so when you get finished piping the first layer in the cones, be prepared to wash up your saucepan, piping tip and batter bowl for the next layer. I tried dividing one batch of marshmallow into the two colors and flavors, but after piping the first color (lime), the second color had already begun to set up. An attempt at re-whipping only made the vanilla layer lax and un-pipeable. Two consecutive batches is the way to go, here. Small glasses make a nice holder in which to stand the cones upright while piping. I used 2 oz. cylinder dessert glasses.
Brush piping gel or clear corn syrup around the top edges of 15 ready made sugar cones. Place the nonpareils on a small plate and then roll the edge of a cone in the sprinkles. Repeat with remaining cones and leave to dry on parchment paper. Have the cones placed upright in glasses and ready to receive piped marshmallow.
Key Lime Marshmallow
Whisk together in a small bowl - gelatin, key lime juice and 1/4 cup cold water. Let set for 5 minutes until gelatin absorbs liquid.
In a saucepan with a candy thermometer inserted, combine sugar, 1/4 cup corn syrup, 1/4 cup water and salt. Place over high heat and bring to a boil. Meanwhile, pour the remaining 1/4 cup corn syrup in the bowl of a standing mixer fitted with the whisk attachment. Heat the gelatin in the microwave or on the stove-top until melted completely and pour into the mixing bowl with the corn syrup. Turn mixer on low and keep it stirring until the sugar syrup is ready.
When the syrup reaches 240F. slowly pour it into the mixer bowl. Increase the speed to medium and beat for 5 minutes, then increase to medium-high and beat 5 more minutes. Finally, increase to highest speed and beat 5 more minutes, until tripled in volume. Add food coloring and beat until incorporated. Immediately scoop marshmallow into the large piping bag - do not tarry here -and quickly pipe the mixture into the cones, swirling in a circular motion as you pipe.
Pink Vanilla Marshmallow
Whisk together in a small bowl - gelatin and cold water. Let set for 5 minutes until gelatin absorbs liquid.
In a saucepan with a candy thermometer inserted, combine sugar, 1/4 cup corn syrup, 1/4 cup water and salt. Place over high heat and bring to a boil. Meanwhile, pour the remaining 1/4 cup corn syrup in the bowl of a standing mixer fitted with the whisk attachment. Heat the gelatin in the microwave or on the stove-top until melted completely and pour into the mixing bowl with the corn syrup. Turn mixer on low and keep it stirring until the sugar syrup is ready.
When the syrup reaches 240F. slowly pour it into the mixer bowl. Increase the speed to medium and beat for 5 minutes, then increase to medium-high and beat 5 more minutes. Finally, increase to highest speed and beat 1-2 more minutes, add vanilla then beat again for 1-2 minutes. Mixture should be opaque and tripled in volume. Add food coloring and beat until incorporated. Immediately scoop marshmallow into the large piping bag - do not tarry here -and quickly pipe the mixture into the cones, swirling in a circular motion as you pipe.
Let cones stand upright in small glasses until set. Dust with marshmallow coating if desired (see notes for coating recipe).
Notes
Combine 3/4 cup confectioners' sugar with 1/2 cup cornstarch and dust the cones with this mixture. This will take away any stickiness and makes them easy to bag in cellophane for party favors.