First, I mixed up a boxed strawberry cake. In this instance, I prefer boxed cake to homemade. I have yet to find a satisfyingly strawberry homemade cake recipe. I have one more marked on my list to try...I'll get back to you on that!
After baking the cupcakes, I began the filling process. I looked up all kinds of filling recipes, which I will experiment with more, but this time I used strawberry jam. I was very, very happy with it as a cupcake filling. To create space for the jam, I used a cupcake corer, which is a tool specifically designed for this job.
As illustrated with the photo, you place the corer on the top center of the cupcake, push down, twist, and remove. The idea is to take the "cored" part of the cupcake and use the top portion to cap the filled area of the cupcake. Easy enough. However, I found that the remains of the cupcake core were a bit of a mess and there was no intelligble cap left to add onto the cupcake.
Next, I filled the cavity with jam using a spoon. Since I had no solid cap to cover the cupcake I improvised by packing some crumbs over the jam.
As an experiment, I also tried using a knife to core the cupcake. This yielded much better results. I cut a circle out of the middle of the cupcake - careful not to to go all the way to the bottom - and had a solid cupcake cap to top the filling. This worked much better.
Really, I'm not sure it make a difference what method you use, or even if it's necessary to cap the cupcake at all, as it will all be smothered with icing anyway. The only problem I foresee with the corer is having to constantly clean it between cupcakes. I stuck with the knife method.
Once I completed the filling process, I piped buttercream frosting onto to each cupcake and added some pink cake sparkles. Then I tried one. And then another. I could have eaten a third, but I do have some self restraint! Filling cupcakes it a very easy process and you should give it a try. I am going to have fun with new combinations of flavors. Enjoy!