Place butter in a medium microwavable mixing bowl. Microwave butter for 30 seconds, or until half melted.
Add sugar, and mix until sugar is fully incorporated in the butter. Add the egg and whisk until fluffy.
Stir in the milk, orange zest, and vanilla.
Add the flour to the bowl. Mix until a lumpy batter is formed. Gently stir in cranberries.
Spray your pie dish with non-stick spray. I use an olive oil spray. Pour the batter in the pie dish. Sprinkle some sugar evenly over the top of the batter to bake a nice sugar-crust on top.