First off make sure she is home, you dont want it to be awkward where one of the kids answer the door and you have to explain why you are dropping something off for their mom. Take her a bottle of wine to thank her for the cookies (really just an excuse for you to be in her yard) while there chat her up, find something that you are both have interests in, kids school, an annoying/weird neighbor. From there at some point ask her if she has been to a new restaurant/movie theater/event in town, hopefully not, then mention that you know lives can be busy being a single parent, but if she could find some time in the next couple weeks(shows her that you are single and you will find out for sure if she is) then ask her if she wanted to go some time. Bam, in her pants in no time.