You can structure your answer using the STAR format when responding to a behavioral question. You begin by describing the Situation, followed next by stating the Task(s) you needed to accomplish. You then move on to the Actions you took and finish your answer by discussing the Results you attained. In this particular question, the interviewer is expecting you to describe both the success you had as well as some challenges you encountered and how you overcame them.

"I was recently tasked with creating an internal system that would allow the organization's employees to make changes in their benefits program using an online application. The stakeholders for the project included the HR Department, Finance, and a representative from a Corporate Leadership team. I kicked off the project with a team meeting to discuss our objectives, project scope, resources, and timelines. Once we understood these elements, I gathered my engineering team and began working on the various architectures required for this system. Due to our experience, we were able to deliver the system's prototype well within the allocated timeline and budget. However, the representatives of the HR Department continued to add additional requirements to the system once they understood the application's capabilities. This scope creep meant that we were continually reengineering both the software and hardware elements of the solution. After several iterations, I was able to lock down the parameters for the project by appealing to the organization's Finance and Leadership teams. The system we created functioned as specified and delivered the results the stakeholders were anticipating."