Bring 1 cup milk to a boil. In a bowl, whisk 1 large egg, 3 large egg yolks and 3 tablespoons sugar; gradually whisk in the hot milk. In a small saucepan, stir the mixture over low heat until slightly thickened. Strain and stir in 1 teaspoon vanilla extract and 1 cup blueberries. Serve warm or chilled.