Preheat oven to 375 degrees F. Grease a 9x13 baking pan.

In a large bowl cream butter and sugar until light and fluffy. Add eggs one at a time beating until well blended.

In a medium bowl combine flour,baking powder and salt and whisk together.

In a small bowl combine milk and water and mix well.

Add flour mixture to butter mixture alternately with milk mixture, beginning and ending with flour mixture. Mix at low speed until well blended.

Gently stir in blueberries and cream cheese.

Pour into prepared pan.

In a small bowl combine all ingredients and cut together with a fork to form crumbs.

Sprinkle over batter.

Bake for 55 minutes of until a toothpick comes out clean and top is golden.

In a medium saucepan over medium heat, combine the blueberries, 1/2 cup of water, sugar and lemon juice. Bring to a low boil stirring frequently.

In a small bowl, mix the cornstarch with 2 tablespoons of cold water.

Slowly stir the corn starch mixture into the blueberries.

Simmer until sauce thickens, about 5 minutes.

Remove from heat and stir in the vanilla and lemon zest.

Can be served warm or cooled.