Preheat the oven to 350 degrees F and line muffin tins with 24 paper liners. For the cupcakes, mix the flour, baking powder and salt in a bowl. Set aside. Then cream the butter and sugar in the bowl of an electric stand mixer for 3-5 minutes until light and fluffy.
Scrape the bowl and add the eggs and vanilla. Beat slowly while adding the flour mixture and milk, alternating between the two. Scrape the bowl again and beat for 10 more seconds. Distribute the batter evenly into 3 separate bowls. Leave one as is. Mix 1 tablespoon cocoa powder into the second bowl. The mix the strawberry extract and a drop or two of red food coloring into the third bowl.
Spoon about 1 tablespoon of each kind of batter into the paper liners. They should be about 1/2 to 2/3 full. Use a toothpick or wooden skewer to swirl the batter lightly. Bake for 15-20 minutes until the tops spring back when touched. Allow the neapolitan cupcakes to cool completely before moving on to the frosting.
For the Neapolitan Frosting: Using a lean mixing bowl, beat the butter until light and fluffy, then slowly add the powdered sugar. The frosting will look clumpy at this point. Keep the mixer running and add the vanilla and 1 tablespoon of cream at a time until it smooths out and is light and fluffy. Scrape the bowl and beat another few seconds.
Distribute the frosting evenly into 3 bowls. Leave one as is. Mix strawberry extract and food coloring into the second. Then mix 1 1/2 teaspoons of cocoa powder and another 1 1/2 teaspoons cream into the third.
Scoop each frosting into a separate disposable piping bag. Seal the tops with rubber bands and snip the tips in the same place on each bag. Then snip the tip of a large zip bag and place a large piping tip down in the bottom. Carefully place all three frosting bags into the zip bag with the ends pressed down in the tip. Now hold the top of the zip bag and squeeze to swirl frosting on top of each cupcake in a circular motion. If the 3 flavors of frosting aren't coming out evenly, adjust the piping bags and continue.