Preheat the oven to 400ºF. Grease a 12 cup muffin tin or line with paper liners.
In a large bowl, combine flour, cornmeal, sugar, baking powder, and salt. Add milk, oil, and egg and stir until just moistened. Divide the batter evenly amongst the muffin tins. Place 1 teaspoon of jam in the center of each muffin. Bake 20 minutes or until a toothpick inserted in a muffin (avoiding the jam) comes out clean.
Allow the muffins to cool slightly in the pan before removing to a cooling rack to cool completely.