Preheat oven to 350°F. Line twelve 2 ½-inch muffin cups with paper bake cups.
In a small bowl beat cream cheese, one of the eggs, 3 Tbsp. granulated sugar, and ½ tsp. of the vanilla with a mixer on low to medium until light and fluffy. Set aside.
In a large bowl stir together next five ingredients (through salt). Using a pastry blender, cut in butter until mixture resembles coarse crumbs. Make a well in center of flour mixture.
In a medium bowl whisk together remaining egg and 1 tsp. vanilla, and buttermilk. Add egg mixture all at once to flour mixture. Stir just until moistened (batter should be lumpy). Stir in blueberries.
Spoon about 1 ½ Tbsp. of the blueberry batter into each prepared muffin cup. Top each with 1 rounded Tbsp. cream cheese mixture.
Divide remaining blueberry batter among cups. Sprinkle with Streusel.
Bake 25 to 28 minutes or until a toothpick comes out clean. Cool in muffin cups on a wire rack 5 minutes. Remove; serve warm or at room temperature. Streusel
In a medium bowl combine flour, brown sugar, and salt. Toss in melted butter until moistened.