Add the softened butter to your bowl in a stand mixer fitted with the paddle attachment or a hand mixer. Cream the butter on high speed until light and fluffy, 2-3 minutes.
Turn the speed down to low and beat in the vanilla.
Mix in the confectioners' sugar, beating at low speed, scraping down the sides with a rubber spatula until fully incorporated.
Beat the heavy whipping cream with a Tablespoon until the desired consistency is reached.
In two small bowls, divide the frosting evenly.
Using a toothpick, dip it into your gel food coloring, or if using a dropper, use one to three drops of each color per bowl.
Gently stir in color until your desired shade of orange and yellow is reached. You can also do one drop of red and one drop of yellow to create an orange if needed.
Press alternating colors along either side of the open bag using a clean piping bag and a star-shaped tip. Twist the bag at the top to seal it and push the frosting down the bag.
Pipe each cupcake with orange and yellow swirls to mimic a fire.
Place pretzel sticks upright around the frosting fire.
Using one toothpick per cupcake, thread two marshmallows on each toothpick.
Roll or sprinkle cinnamon on the marshmallows to create a toasted effect, optional, and place in your completed cupcake.