In a microwave-safe cup, whisk together the flour, sugar, cocoa powder, baking powder, and salt until well combined.
Add the orange zest, vanilla extract, milk, and vegetable oil to the cup. Mix the batter until smooth and creamy.
Fold in the chocolate chips to distribute them evenly throughout the batter.
Microwave on high for 2 minutes, or until the cake has risen and set in the center.
Remove from the microwave and let cool for 1 minute, allowing the aromas of orange and chocolate to meld together.
Serve warm, garnished with additional orange zest or a drizzle of orange glaze, if desired.