Place a large baking sheet on your counter and sift 1 cup of cornstarch and 1 cup of powdered sugar over the pan into an even layer. The smoother the layer is, the smoother the bottom of your marshmallows will be. If you don't have a sifter, whisk the powdered sugar and cornstarch together in a bowl, then pour them onto the baking sheet. Set aside.
In the small bowl, add 2 Tbsp cold water and sprinkle 1 1/2 tsp of powdered gelatin evenly over the surface. Set aside to bloom.
In a large bowl, beat 2 large, room temperature egg whites (70g) on a medium-high speed with a hand mixer until they look foamy and reach the soft peak stage. Then, gradually mix in 3 Tbsp granulated sugar (35g) at a medium-high speed for about a minute, or until the mixture looks fluffy and has stiff peaks. Make sure the egg whites are fully at room temp, or else they will take a lot longer to whip up.
In a medium saucepan, combine the remaining 1/3 cup granulated sugar (65g), 1 Tbsp corn syrup (20g), and 1 Tbsp + 1 tsp water (20g). Cook over medium-high heat, stirring with a rubber spatula until the sugar dissolves and the mixture comes to a boil. Remove from heat.
With your mixer on low speed, slowly pour the hot syrup into the egg-white mixture in a steady stream. Gradually increase to high speed and whip until the marshmallow looks thick, fluffy, and glossy (it usually takes me about a minute).
Heat the bloomed gelatin from step 2 in the microwave for 10-15 seconds, or until it just becomes fluid. You don't want to overheat the gelatin, or it can prevent your marshmallows from setting properly. With your mixer on low speed, pour the warm gelatin into the egg-white mixture and mix until the gelatin is just incorporated. Scrape the sides and bottom of the bowl with a rubber spatula to make sure it's properly combined.
Then fold 1 tsp vanilla extract and a pinch of fine salt into the mixture with a rubber spatula.
Scoop about 1 cup of the uncolored marshmallow mixture into a small piping bag and seal the top of the bag with a rubber band. Cut a 1/4 inch or 1 cm opening at the base of the bag, then set it aside.
Color about 1/2 of a cup of the marshmallow mixture with orange gel food coloring, then place it into a small piping bag and seal the top of the bag with a rubber band. Cut a 1/8 of an inch or 2 mm opening at the base of the bag, then set it aside (angle the opening at the base of the bag upward against the edge of a plate to prevent any from flowing out).
Color about 3/4 of a cup of the marshmallow mixture with pink gel food coloring, then place it into a small piping bag and seal the top of the bag with a rubber band. Cut a 1/4 inch or 1 cm opening at the base of the bag, then set it aside.
Color about 1/4 of a cup of the marshmallow mixture with black gel food coloring, then place it into a small piping bag and seal the top of the bag with a rubber band. Cut a VERY small, 1 mm opening at the base of the bag, then set it aside.
Color the remaining marshmallow mixture a light grey color using a small squirt of black gel food coloring. Scoop it into a large piping bag and seal the top of the bag with a rubber band. Set aside.
Then pipe the marshmallow penguins on the prepared baking sheet, using the pictures above as a guide. Start with the grey body, then add the white tummy, followed by the feet and beak, eyes, heat, and then flippers. I piped some standalone penguins and some pairs. Mine were about 1 1/2 inches tall.
Note: If you're having trouble piping or the marshmallow mixture isn't smooth when you pipe it, heat the bag in the microwave (as long as you aren't using metal piping tips) for 2-5 seconds. It softens SUPER fast, so do this in tiny, 2-second intervals!!), or run the bags under some hot water.
Let the marshmallows sit at room temperature for a couple of hours or until they're firm. Once they're set, brush some of the cornstarch/powdered sugar mixture on top of them to prevent sticking. Gently brush them off with a fan brush or very soft brush and enjoy.