Hello cute little cardigan!
I found this pattern called the Abigail Baby Girl Cardigan and loved the simplicity of it. A cardigan with no fuss and perfect to overlay any type of dress.
For the bow,
1: Ch 15. Starting from the 2nd chain from the hook, sc 14.
2 – 5: Turn, ch 1, sc 14.
sc around the rectangular piece of work. Pinch the the centre so you can make a bow and tie yarn around it, so that the bow remains secure.
Sew one end of the bow on to the fabric, and for the other end I used snap fastener, so that the button remained nice and hidden beneath the bow.