Grease an 8x8-inch pan with vegetable oil and line with parchment paper. Lightly grease the parchment paper as well and set the pan aside.
Pour 1/2 cup of the water in a small bowl and sprinkle the gelatin over the surface. Set aside to gel.
Place the granulated sugar, corn syrup, honey, cinnamon sticks and 2 teaspoons of the ground cinnamon in a large saucepan. Whisk to combine. Place the pan over high heat and bring to a boil. Insert a candy thermometer and heat the mixture to 122°C/252°F without stirring - the stirring will cause the sugar to crystalize. Remove the mixture from the heat and pour into a stand-mixer fitted with a whisk attachment. Let the mixture cool to 100°C/212°F.
While the sugars are cooling, melt the gelatin in a double boiler until liquid. Pour the gelatin into the cooled sugars and whisk on high for 8 minutes.
Spoon the marshmallow into the prepared pan and, using a greased spatula, spread the mixture to create an even layer. Take another piece of greased parchment paper and press it on top of the marshmallow mixture to create a flat, even surface. Place the pan in the fridge and let sit overnight.
Once the marshmallow is set, whisk the remaining cinnamon, confectioner's sugar and cornstarch together in a small bowl. Remove parchment paper and dust the surface of the marshmallows with the cornstarch mixture. Invert the pan on a cutting board. Peel the remaining pieces of parchment from the marshmallows and dust the remaining sides with the cornstarch mixture.
Using a greased knife, cut the marshmallows into 25-30 squares. Dust the finished squares in more of the cornstarch mixture. Store in a tightly sealed container in the fridge until ready to use.