This is another important ingredient , if your butter is warm or too cold, it will not be creamy when you mix it with sugars. So your butter needs to be at room temperature so it can be whisked easily. But not to warm that it turns into greasy mixture when mixed with sugar. It should be creamy. The butter at cold room temperature will also rise well. So, If you keep butter on the counter around 30-45 minutes in advance. It works best. In other case, just heat butter in microwave for 15 seconds. And rest it for few minutes before you begin. You can replace butter for margarine. (I've tried it so I know you can make cookies with margarine but use butter for best taste and texture.)
Try to use best quality chocolate chips. You can also use your favourite chocolate and chop it but keep it in fridge, until you mix. So it’s hard and doesn’t melt in batter.
If you are using a stand mixer, this tip is for you. Avoid over beating of eggs in cookie dough. You will fill too much air in cookies and when they will cool after baking, they'll go flat. So annoying!
8-10 minutes works best most of the time for me. But ovens behave differently. So, set your timer to 6 minutes and then look for visual sign of completion of baking. Visual signs win always. I keep staring at my cookies when they bake and it's so satisfying. You need light brown edges and centre will be under cooked for soft cookies. When you lift the cookies from baking sheet and transfer to wire rack, they’ll be very soft but they’ll firm up as they cool. For chewy cookies, you edges will be brown and center will be set.
You can bake without baking paper but it really helps and doesn't allow cookie to spread too much. Flat cookie is crispy and chewy instead of being soft and gooey. Another reason is the extra layer between the metal tray and cookie allow them to get golden instead of getting too dark brown or burn.
You can add your favourite nuts in cookies without altering anything in recipe. For around 3 cup flour batch of cookie you may add up to ¾ cup nuts of your choice.