In a medium bowl,whisk together ¼ cup all-purpose flour, ¼ cup granulated sugar, 2 tablespoons cocoa powder, ½ teaspoon baking powder, and ⅛ teaspoon kosher salt. Add ¼ cup whole milk, 3 tablespoons vegetable oil, and ½ teaspoon vanilla extract and whisk to combine.
Add 2 tablespoons semisweet chocolate chips to the cake batter and stir to combine. Evenly divide the cake into two 8 to 12-ounce mugs.
Cook one mug at a time on the microwave on HIGH power for 60 seconds. Check the cake to see if it sets in the center, if not, microwave for 15 to 30 more seconds.