Shortbread!

So over the years I have given baking shortbread a go, ever time I bake them however it turns out pretty bad. 

The first couple times I tried I put milk in them, at the time the dough was not forming so I did what I would normally do, add milk (this is what my Mum said to do when things weren't combining) at the time I didn't know you weren't suppose to add milk, otherwise it wouldn't be a shortbread, so yeh that was the first fail! So today I tried to bake them again, my Mum however helped, she is a very good baker (guess it runs in the family not with me though) and it was going great we put it in the oven, left it to cook then when it was done I took it out and left it to cool, I went for a bath. When I came back it looked great, then Mum put it onto the tray and.... crumble! Great! Well it tastes nice, but I'm just not cut out for baking. My Mum, Grandma and Auntie are all great bakers, I shall leave it to them and Mary Berry!