In a liquid measuring bowl, whisk together 3/4 cup whole milk, 2 eggs, and 1/4 cup strawberry milk powder.
Turn your mixer to its slowest speed, and gradually pour half of the liquid mixture (from the third step) into the butter/flour/sugar mixture (from the second step) and mix until just combined. Turn off the mixer and scrape down the sides of the bowl. Once the batter from the sides of the bowl have been incorporated, turn the mixer back on to its slowest speed and gradually pour in the remaining liquid, continuing to mix until just combined. Use a rubber spatula to give the batter a few more mixes by hand to ensure that the batter is smooth and combined.
Use a 1 tablespoon-sized cookie scoop to spoon 2 tablespoons of batter into the prepared cases (or, if you don't have a cookie scoop, fill the cases up to 2/3rd full) and bake for 20 - 25 minutes in the preheated oven or until the sponge bounces back when lightly touched.
Allow the cakes to cool slightly on a cooling rack, before turning out on to the rack to cool completely.
Gradually pour the milk mixture (from the second step) into the sugar and butter mixture (from the first step) and mix on a low speed until the liquid mixture has been combined into the sugar and butter. Then, turn up the mixer and beat the mixture for 5 minutes, until the frosting is light and fluffy. Do not overbeat, or the mixture will be too liquidy and runny!
Use a 1 tablespoon-sized cookie scoop to spoon 2 tablespoons of frosting on each cupcake. Make sure the cupcakes are completely cool before you start frosting — otherwise they'll be soggy and I'll cry for you.