Mix the cream cheese, egg yolk, sugar, and vanilla and set aside
Place the puff pastry on a lightly floured surface. Roll it out slightly, then, cut the puff pastry in half lengthwise, then cut each half into 3 equal pieces. Use a knife to score (but not completely cut through) a border into each piece.
Place on a baking sheet lined with a silicon baking mat or parchment paper. Spoon one spoonful of jam within the border, then top with the cream cheese mixture and top with the sliced strawberries.
Let chill in the fridge for 20 minutes
Preheat the oven to 400 degrees.
Combine the egg and milk to create an egg wash, then brush over the border of the puff pastry and sprinkle with sugar.
Bake for 15-20 minutes or until the danishes are puffed up and golden brown. Remove from the oven and allow to cool for 5 minutes before serving.
Sprinkle with powdered sugar if desired.