Preheat oven to 400 degrees F.  Line a muffin tin with paper liners or oil it very, very well.

Make the jam.  In a small saucepan, stir together 2 cups blueberries, syrup, and lemon juice.  Bring to a boil over medium heat, and cook stirring frequently until the berries burst and the juices thicken.  Pour into a bowl and cool while you make the muffins.

In a large bowl stir together sugar, eggs, oil, and vanilla until well combined.  Stir in half the flour, followed by half the milk.  Stir in the remaining flour, baking powder, cardamom, ginger, and salt.  Finish the batter with the milk, and finally the remaining 2 cups of blueberries.

Fill the muffin cups half way full, top with one teaspoon of blueberry jam, and then fill with remaining batter.  Finish by topping each muffin with another teaspoon of jam and bake about 18 minutes until golden brown and a toothpick inserted in the center comes out clean or with a few crumbs.

Serve warm or cool completely in the pan.  Muffins may be stored in an airtight container at room temperature for up to 4 days or frozen, wrapped in parchment and foil and placed in a zipper bag for up to 3 months.  Thaw in the microwave about 1 minute.