Hello, I have not yet found a tutorial for this technique but it is fairly simple. It's just a matter of using a shape (heart in this case) as an outline, then on a new layer create some text. Copy the text layer and rastorize the copy. Use the rectangular marquis tool to separate each letter to its own layer. Then use the transform > warp function to warp the individual letters into the desired shape. You can then combine/merge the individual letter layers into one "warped" layer and then add a layer style.
Here is a very quick example I made using the word hello and a heart shape.
Here are the layers used......
The original text I separated using the rectangular marquis tool.....
The combined/merged warped text, the heart shape, and the blue BG.
Of course you could just use the text like what's on the girls shirt......