This chocolate mug cake has a rich cakey exterior and a molten chocolate center. If that's not enticing enough, this easy dessert is ready in just 15 minutes.
In a medium bowl, whisk together the flour, sugar, cocoa, baking powder, and salt.
Break 1/2 of the chocolate into rough 1-inch (25-mm) pieces. In a 12-ounce (355-ml) microwave-safe mug, combine the chocolate pieces with the butter. Microwave at 50 percent power, stirring often, until melted, 50 seconds to 2 minutes.
☞ TESTER TIP: Once the butter has melted, a good vigorous stir really helps melt the chocolate.
Add the flour mixture, egg, and vanilla and mix until smooth and well combined, being sure to scrape corners of mug.
Microwave the cake batter at 50 percent power until batter has doubled in size, 50 to 70 seconds.
Break the remaining chocolate into 2 pieces and press it into the center of the cake with the top of the chocolate pieces flush with the top of the cake.
☞ TESTER TIP: It's important to make sure the chocolate pieces reach completely through the whole cake—top to bottom.
Microwave the cake at 50 percent power until the cake is firm but the top is just wet to the touch, 15 to 30 seconds. The cake may rise above the edge of the mug but won’t overflow.