Preheat oven to 350 degrees. Line 12 standard muffin cups with paper liners.
In a large mixing bowl, whisk together 1½ cups flour, baking powder and salt.
In the bowl of an electric mixer, preferably fitted with a paddle attachment, cream the butter and sugar together on medium speed for 2 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 sides of the bowl after each addition. Turn the mixer to low, add half the flour mixture, then the milk and finally the remaining flour mixture. Add the vanilla extract and mix well. Scrape the sides and bottom of the bowl with a spatula to make sure all the ingredients are fully combined.
Place ½ cup of blueberries in a small mixing bowl, add 1 tablespoon of flour and toss the blueberries with the flour. Add ¾ cup of batter and gently fold the blueberries into the batter. Divide the mixture among the prepared muffin cups and smooth down the batter with a small offset spatula or a moistened finger, making sure to spread the batter all the way to the sides.
Place ¾ cup of batter in a small bowl, add the remaining tablespoon of flour and the maraschino cherry juice. Mix well. Gently spoon this batter on top of the blueberry layer. Even out the batter and spread all the way to the sides. Gently spoon the remaining batter on top of the cherry layer and spread as before. Bake for 20 – 25 minutes or until the tops of the cupcakes are starting to brown and a tooth pick inserted into the center comes out clean. Let the cupcakes cool in the pan for 5 minutes then remove to a wire rack to finish cooling.
While the cupcakes are cooling, make the frosting.
In the bowl of an electric mixer, preferably fitted with a paddle attachment, beat the ½ cup butter with the 1/8 teaspoon salt on high speed until creamy. Add the powdered sugar, vanilla and lemon juice and mix, starting on low and increasing the speed until fully combined and fluffy.
Pipe or spread the frosting onto the cooled cupcakes and garnish each cupcake with a maraschino cherry, the remaining blueberries and some sprinkles.