Preheat oven to 400 degrees.
Put the butter in a 15" cast iron skillet and place it in the preheating oven. Remove it from the oven once the butter has melted.
Cut the cream cheese into 1/2 inch pieces and set aside.
Add the eggs, milk, oat flour, vanilla, and salt to a large mixing bowl and whisk together until smooth.
Pour the batter into the skillet with the melted butter.
Sprinkle the blueberries and cream cheese pieces on top and place in the preheated oven.
Bake for 30 minutes or until the edges are starting to turn brown.
Enjoy warm with toppings of your choice.