Preheat the oven to 350 F and line your baking tray with cupcake liners and keep aside.
In a large mixing bowl, combine flour, baking powder, and salt and mix until well incorporated.
In another bowl add oil, sugar, and vanilla extract and mix well.
Now, add the egg and milk to the wet mixture and mix until combined.
Add the flour mixture to the wet mixture in batches and beat using electric hand mixer on low until just combined.
Scoop out the batter using an ice cream scoop, and fill your liners till 3/4 full.
Bake in a preheated oven for 22-25 minutes or till a toothpick inserted in the middle comes out clean. Let the cupcakes cool for 5 minutes in the baking tray before transferring them to a wire rack to cool completely.
Once the cupcakes are completely cooled, using the back of a piping nozzle, make a cut at the centre to create a well and remove that part (don't throw it away).
Fill it with jam generously, and close it using the cut-out part.