In a medium saucepan, heat the blueberries over medium heat until they soften and their juices release (about 3-4 minutes).

In a separate bowl, whisk sugar, cornstarch, and salt together. Stir dry mixture into the blueberries and continue stirring until mixture thickens. Remove pan from heat and stir in lemon juice. Pour blueberry filling into prepared dish.

Preheat oven to 350ºF and spray a 9x13-inch baking dish with nonstick cooking spray.

Using a stand mixer fitted with a paddle attachment, mix cream cheese, powdered sugar, milk, vanilla, and almond extract until smooth. Pour mixture into a small ziploc bag, and snip the tip off. Evenly pipe cream cheese filling over the blueberry filling.

Sprinkle cake mix over cream cheese filling. Evenly distribute the sliced butter pieces over the cake mix. Bake for 40 minutes, or until bubbly and golden brown on top. Allow to cool for at least one hour before serving. Store leftover cobbler covered in the refrigerator for up to 5 days.