In medium bowl, stir 1 1/4 cups Bisquick mix and the brown sugar with whisk. Make well in center of mixture. In small bowl, stir milk, butter, vanilla and egg with whisk until well blended. Add to dry ingredients, stirring just until moistened. In small bowl, lightly toss diced strawberries and 1 teaspoon Bisquick mix. Stir into batter; spoon batter evenly into muffin cups.