Spray a 9"x13" pan lightly with unflavored oil to prevent sticking. You can also spray molds to make fun shapes! Silicone molds work best for easy removal.
Add ½ cup cold water and add 1 tsp butter extract, and 2 tsp vanilla to a stand mixer or large bowl.
Add 2 Tbsp (3 envelopes, approx 21g) gelatin into the bowl as you whisk lightly to incoporate it so it doesn't clump.
In a heavy saucepan, add the remaining ½ cup cold water with 1 cup white sugar, 1 cup brown sugar, ½ cup corn syrup, and ¼ tsp salt. Cook over low heat, stirring gently until sugar dissolved.
Increase heat to medium and boil without stirring until mixture reaches 240°F, about 12 minutes. As soon as it reaches the right temperature remove from the heat.
Begin whisking the bloomed gelatin on slow speed. Pour the sugar mixture over the gelatin bloom stirring until dissolved evenly. Then add the remaining sugar mixture.
Beat mixture on high speed until white, thick, and nearly tripled in volume. This should take approximately 6-8 minutes in a stand mixer, and roughly 10 minutes with a hand mixer.
Working quickly, spread the mixture into the prepared baking pan (or pipe into molds if desired) and smooth with an oiled spatula.
Allow to stand, uncovered for at least 4 hours up to one day.
Mix together 1 Tbsp cinnamon with ⅛ cup each cornstarch and powdered sugar. Turn out the marshmallows and using a pastry brush, coat with the sugar mixture. Cut into desired sizes, I like to trim the edges, and then cut into 5 columns, Cut each column into squares, makes roughly 25. Brush each individual marshmallow with the sugar mixture on all sides to prevent sticking.