Preheat the oven to 180°C (350°F).
In a mixing bowl, beat together the margarine, vanilla extract, and sugar until creamy and fluffy.
Stir in the eggs and milk until well combined.
In another bowl, mix together the flour and baking powder. Gradually add the flour mixture to the wet ingredients, stirring until just combined.
Gently fold in the blueberries until evenly distributed throughout the batter.
Divide the batter evenly into 12 muffin cups lined with paper liners.
Bake in the preheated oven for about 15-20 minutes, or until a toothpick inserted into the center of a muffin comes out clean.
Allow the muffins to cool slightly before serving. Enjoy your delicious and Weight Watchers-friendly blueberry muffins!