Make Cream Cheese Filling (using ingredients listed under cream cheese filling)
Beat cream cheese and granulated sugar in medium bowl using electric hand mixer until smooth & creamy.
Mix in egg and vanilla until just combined. Set aside.
Prepare Cake Batter (using ingredients listed under cake batter)
Preheat oven to 350 degrees. Spray a 9 x 5 x 3 inch loaf pan. Set aside.
Cream together butter and sugar in a large mixing bowl until light and fluffy. Beat in eggs one at a time. Add vanilla and beat until just combined.
In a separate medium mixing bowl whisk together flour, baking powder, and salt.
Add dry ingredients to wet ingredients, alternating with milk. Mix until combined. Do not overmix. NOTE: mix in 1/3 dry & 1/2 milk, then 1/3 dry and rest of milk, finish with rest of dry.
Mix in 1/2 cups of fresh blueberries into the cake batter.
Assemble loaf
Pour half of the cake batter into prepared loaf pan and smooth evenly.Spoon half of the cream cheese mixture onto cake batter and smooth evenly.
Add remaining cake batter on top of the cream cheese mixture and smooth evenly.Top with remaining cream cheese mixture and spread evenly. Top with remaining 1/2 cup fresh blueberries.
Bake in preheated 350 degree oven for 50-60 minutes until toothpick inserted into cake portion comes out clean.
Let cool in loaf pan for 10 minutes. Run a knife around the inside edges of loaf pan to loosen cake. Invert cake to a plate, then invert again to a serving platter. Cut into slices and enjoy.