This piece, "Ah! vous dirai-je, maman" is the reason I don't play piano. Many years ago a kindly neighbor asked if I wanted to learn to play the instrument. I said sure and she started playing with one finger and I'm thinking I can do that and all of a sudden she segues into the variations and yikes!
Here's the Rousseau YouTube channel with "Mozart - Twinkle Twinkle Little Star (12 variations on Ah vous dirai-je, Maman)"
The sheet music gets rather dense with notation (variations 4, 5, and 6):
And from Atari