Preheat oven to 350 degrees. Line 12 standard muffin cups with paper or silicone cupcake liners .
In a large mixing bowl whisk together 1½ cups of the gluten-free flour blend, baking powder and salt.
In the bowl of an electric mixer, preferably fitted with a paddle attachment, cream the butter and sugar on medium high speed for two minutes or until light and fluffy. Scrape down the sides of the bowl and add the eggs, one at a time, mixing well and scraping down the bowl after each addition. Turn the mixer to low and add half of the flour mixture, then the 7-Up and finally the rest of the flour mixture. Add the vanilla extract and mix. Scrape the sides and bottom of the mixing bowl well to ensure all the ingredients are fully incorporated. Do not be concerned if the batter looks a little curdled.
Take a ½ cup of the batter and put in a small bowl. Add the remaining 1 tablespoon of flour, the maraschino cherry juice and enough red food coloring to turn the batter red. Stir well. Divide the batter evenly between the prepared pans (about 1 big teaspoon per cup). Gently spoon the remaining batter on top of the red batter trying not to mix the two colors but to keep in layers.
Bake for 15 – 20 minutes or until the tops of the cupcakes are slightly springy and a toothpick inserted into the center comes out clean. Let cool in the pan for 5 minutes then remove to a wire rack to finish cooling. (The cupcakes will puff up a bit while cooking because of the 7-Up.)
While the cupcakes are cooling, prepare the frosting.
In a mixing bowl of an electric mixer, preferably fitted with a paddle attachment, beat the butter and salt on high speed until creamy. Sift in the confectioners’ sugar and mix on low until fully combined. Add the vanilla, lemon juice and maraschino cherry juice. Mix to combine.
Pipe on or frost the cupcakes with the frosting and top each cupcake with a maraschino cherry.