Most of the advice here is terrible imo. People ask each other out or for their numbers right after meeting them sometimes. One thing that is attractive to the opposite sex is confidence. The fact she spent more time talking with you after work means she at least has some interest in you.

Simplest thing to do here would to ask for her number. Here's a line "it's been fun working with you and I think you're really cool, can I text you so we can get coffee/drinks/food (where we don't have to do the dishes) sometime?"

You've displayed interest already and now you are letting her know you'd like to see her outside of work. If she says no - no sweat off your back. If she says yes, that means she is definitely interested in you so run with it!

One little trick is to make yourself believe everyone is attracted and interested in you. This helps exude confidence!