According to wikipedia, "..Spatchcock is the traditional word for the French term "poussin", a juvenile chicken".
Bearing this in mind, I guess it would be a tautology to describe the picture above as a spatchcocked poussin. Although, it is exactly that: a poussin that has been spatchcocked, or butterflied.
Once you have done that (and there are myriads of videos on the web of how to butterfly a chicken), prepare your weights that go on top of the bird while it's cooking. Where I come from, they use a clean brick, as simple as that. Another solution (and I have just tested it positive) is to take off the knob of your pan's lid so the surface is flat, and read further..
Next step:
Put the pan on medium heat, butter well, and put the bird in when it's hot. Put your prepared lid on top of the bird, former knob side down.
Now put a saucepan full of water on top of that and press down. This is your weights.
Cook for ..hmm, you know what, I didn't time it, but if I had to guess, about 10 minutes. Disassemble saucepan-lid setup, flip the bird over, and re-assemble again. Cook the other side for the same duration.
For the salad, toss together salad leaves of your choice (original recipe says rocket), crumbled gorgonzola and sundried tomatoes. Drizzle with balsamic vinegar, olive oil and a tablespoonful of sesame seeds.