Preheat oven to 350 degrees F (175 degrees C). Grease 9 cups of a muffin tin; place tin on a baking sheet.
Divide croissant cubes evenly among greased muffin cups. Press strawberries into and on top of the cubes.
Beat cream cheese, white sugar, milk, egg, and vanilla extract together in a large bowl until smooth. Pour over each muffin cup slowly until croissant cubes and strawberries are fully soaked.
Bake in the preheated oven until set and evenly browned, 30 to 40 minutes. Cool in the muffin tin for 5 minutes, then transfer to a wire rack to cool completely, about 30 minutes. Dust with confectioners' sugar before serving.
You should have about 5 1/2 cups of croissant cubes. If using fresh croissants, spread cubes on a baking sheet lined with parchment paper and toast them in the preheated oven to dry them out, about 5 minutes.
Substitute frozen strawberries (thawed) for the fresh if preferred.
Parchment can be used for easier cleanup/removal from the pan.