Spray a 9"x13" pan lightly with unflavored oil to prevent sticking. You can also use butter, shortening, or any other unflavored fat.
(Optional) For flat, smooth tops on your marshmallows, tear a piece of parchment paper or wax paper large enough to fit the surface of your 9"x13" pan. Spray or coat one side with unflavored oil and set aside.
Add ½ cup cold water and add 1½ tsp raspberry flavoring, and 1 tsp vanilla bean paste 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 2 cups white 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.
If using food coloring, add several drops of red food coloring and fold gently in. Continue until desired pink-ness is reached. Avoid overmixing, as this will deflate your marshmallow and make it denser.
Working quickly, spread the mixture into the prepared baking pan (or pipe into molds if desired) and flatten with an oiled spatula or prepared parchment paper.
Allow to stand, uncovered for at least 4 hours up to one day.