Preheat the oven to 350 degrees Fahrenheit.
Beat the butter and sugar until fluffy. Add the egg and vanilla.
Mix in the flour and baking powder to form a soft dough.
Roll the dough into balls and place on a baking sheet. Flatten each ball slightly and use your thumb to make a shallow indent in the center.
Fill each indent with a small scoop of strawberry jam.
Bake for 10 to 12 minutes. Let cool completely.
Whisk the powdered sugar and milk together to make a glaze. Drizzle over the cooled cookies and top with sprinkles.