The need to expand computer science learning for all students has led to an increase in professional development (PD) opportunities for teachers. The COVID-19 pandemic, however, necessitated changes in well-established PD programs and a shift to virtual delivery. In this work, we describe our transition to a virtual PD institute, including the topics and design principles guiding the institute. We also examine how participation in the virtual PD institute influenced teacher outcomes. Data were collected from two cohorts of teachers. Data sources included surveys (N=30), lesson plans (N=22), and interviews (N=17) from a purposeful sample of participants. Findings gleaned from quantitative and qualitative analysis suggest an increase in teachers' knowledge and self-efficacy while highlighting the affordances of virtual PD most valued by teachers. Findings have implications for research and practice.