What went wrong with my cookie dough? This is my latest attempt at making chewy cookies.

I used:


220 g butter, melted
200 g brown sugar  
100 g white sugar
320 g all-purpose flour 320g 
1 whole egg + 1 yolk 


I don't understand why it turned to a dark color. Is it because of the brown sugar? Chewy cookies need a high brown to white ratio, don't they?

One more thing I noticed while mixing was that the sugar (both white and brown) didn't mix easily with the melted butter. 

Also, are chewy cookie and softbaked cookie the same thing?

Here's the result after baking for 12 minutes

form the look of its bottom i think there might be something wrong during beating sugar in melted butter,isn't it?
Your egg and butter mix has curdled/split you need to put it in a fresh floured bowl and keep mixing till smooth.

The brown is, as you mentioned, the brown sugar. Nothing to worry about. 

Personally I wouldn't use melted butter at all. Rather I would use soft butter. Creaming sugar and butter with melted butter is impossible, especially if the butter is melted to the extent where the fat and milk have separated.

Soft bake is soft, like cake. Chewy bake is ... Chewy, like brownies.