Preheat the oven to 350°F and line the muffin tin with paper cupcake liners.
In a medium bowl whisk together the flour, baking powder, baking soda, and salt until well combined.
In a large mixing bowl beat the softened butter and granulated sugar with a mixer on medium speed until light and fluffy, about 2 to 3 minutes.
Add the eggs to the butter mixture one at a time, beating well after each addition, then mix in the vanilla extract.
Add the dry ingredients to the wet mixture in two additions, alternating with the milk, beginning and ending with the dry ingredients, mixing on low just until combined.
Scrape down the sides of the bowl and gently fold the batter with a spatula to ensure it is smooth and evenly mixed without overmixing.
Divide the batter evenly among the 12 cupcake liners, filling each about two-thirds full.
Bake the cupcakes for 16 to 18 minutes, or until a toothpick inserted into the center comes out clean.
Remove the muffin tin from the oven and let the cupcakes cool in the pan for 5 minutes.
Transfer the cupcakes to a wire rack and let them cool completely for at least 25 minutes before frosting.
For the frosting, beat the softened butter in a large bowl on medium-high speed until creamy and pale, about 2 minutes.
Gradually add the powdered sugar, about 1 cup at a time, mixing on low after each addition until incorporated, then increasing to medium speed.
Add the heavy cream, vanilla extract, and salt, then beat on medium-high speed for 2 to 3 minutes until the frosting is fluffy and spreadable.
Divide the frosting evenly into two medium bowls.
Tint one bowl with red gel food coloring a drop at a time, stirring until a soft pastel pink is reached.
Tint the second bowl with green gel food coloring a drop at a time, stirring until a soft pastel mint color is reached.
Transfer the pink frosting to one piping bag fitted with a piping tip and the mint frosting to a second piping bag.
Once the cupcakes are completely cool, pipe swirls of pink frosting on half of the cupcakes and mint frosting on the remaining cupcakes, or alternate colors on each cupcake as desired.
Sprinkle the frosted cupcakes with pastel sprinkles if using.
Let the frosted cupcakes rest at room temperature for 5 to 10 minutes so the frosting slightly sets before serving.