In a microwave-safe mug, add the all-purpose flour, granulated sugar, cocoa powder, baking powder, and sea salt. Use a small whisk or fork to thoroughly mix these dry ingredients until there are no lumps or dry pockets remaining.
Next, incorporate the creamy hazelnut spread into the dry mixture. Gradually pour in the milk, vegetable oil, and pure vanilla extract. Stir with a spoon until the mixture is well combined and smooth, ensuring there are no streaks of flour or cocoa powder.
For an extra crunch, gently fold in a handful of chopped hazelnuts into the batter, which will provide delightful texture in every bite.
Place the mug in the microwave and cook on high for approximately 1 minute and 30 seconds. To check for doneness, gently press the center of the cake; it should bounce back. If it still appears soft, continue microwaving in 15-second increments until completely set.
Once cooked, let your mug cake cool for about 1 minute. For a luscious finish, top with a generous swirl of additional hazelnut spread and sprinkle with more chopped hazelnuts for an attractive presentation.
Notes
Serve immediately in the mug or transfer to a plate. Pair with vanilla ice cream for a delightful contrast.