Designing and building great, innovative user experiences that end users love is hard. Integrating user experience design process into Agile software development also poses unique challenges. We present a process that we have iteratively developed on the Visual Studio and Application Insights product teams at Microsoft that integrates well into common Agile software development practices, and that produces design outcomes that are highly rated by end users. The key to this process is an adaptation of the 10:3:1 iterative design loop, which deliberately explores multiple design points in the design space, and then iteratively refines and winnows these designs into a final design via several iterations. We present how to scale this process to large development teams of 180 full time software engineers that are using Agile software development practices, working in a continuous delivery mode, collaborating with a design team of 3 or more designers, based on our product development experiences. We present practical considerations that helped make this process work well at Microsoft, as well as key pitfalls to avoid. Finally, we present processes for maintaining the consistency and predictability of user experience designs across multiple agile teams working in parallel, without creating centralized bottlenecks, and while still enabling individual teams to innovate and get customer feedback quickly for iterative improvement.