Preheat the oven to 180°C (350°F). Grease or line a loaf pan or square baking dish.
In a large bowl, whisk the eggs with a pinch of salt until lightly frothy.
Add sugar, milk, oil, and vanilla extract. Mix well until smooth.
Gradually add flour and baking powder, stirring just until combined and the batter is smooth.
Pour the batter into the prepared baking pan.
Spoon dollops of jam over the surface and use a skewer or knife to swirl it gently through the batter.
Bake for 30–35 minutes or until a toothpick inserted in the center comes out clean.
Let cool slightly before slicing. Serve warm or at room temperature.