get a microwave safe mug! if it's a short mug, get a plate to put underneath for when the cake overflows.

put about six spoonfulls of flour in your mug, or pour it until it's like a fourth of the volume of the mug. trust me

go for about two spoonfulls of sugar!

for small mugs, add a shallow spoonful of baking powder. for large mugs, go for at least one big spoonful. you may have noticed this is the only thing making the cake rise, so make sure you tell it it's doing a great job.

take a fork and mix those dry ingredients! you might think "oh, i can just use a spoon!" do not do this. you Will end up with dry powdery bits at the bottom of your mug hiding in the corners and ruining the last bite of your cake. target those corners at the bottom the most!! they won't get away with it this time!!!

add your oil first! you're going for about one-one and a half spoonfuls, but don't get a spoon dirty for this! just pour and trust your heart. i believe in you!

add a rough spoonful of jam! just toss it in there!

add your milk or other watery liquid! do this little by little while mixing until it's a consistency that makes you think "wow, that's cake batter!" if you go too far and end up with soup, just add some more flour and keep trying. it's ok! and try to break up the jam evenly so that the batter changes colors! for some reason, whenever i use raspberry jam, my cake ends up bluegreen

now that your batter is all mixed, take a second spoonful of jam and gently plunk it in the middle of your cake. try to get some batter on top of it, so it's hidden in the center. if it breaks up, it's okay! it's going to get really hot in there, so you don't need to use that much jam. just enough for a fun suprise :)

take the fork out and THEN put it in the microwave for 2-3 minutes! keep an eye on it in case it spontaneously combusts or leaps out of the mug. not so that you can do anything about it, but just because it would be cool to see that happen. also this is a good time to wash your fork

your cake probably won't be finished cooking the first time around. depending on the weather, altitude, and humidity, your ideal microwave time will be different and unique. now take your clean fork and poke around in the middle. if it's still kinda soupy, microwave it again for another thirty seconds and repeat until you think "i'm hungry enough to eat this now". remember, there's no eggs, so the only problem with eating your cake soupy is that the baking powder will fizzle in your mouth. and the uncooked flour.

if you're using a massive mug, you may want to push the soup in the middle out to the edges, making your cake a bowl shape. this will kill the suprise but it's ok, having your cake cooked is more important.