Preheat oven to 350 degrees Fahrenheit.

Beat butter and sugar until fluffy; add egg and vanilla.

Mix in flour and baking powder until soft dough forms.

Roll into balls; place on a baking sheet, flatten slightly, and press a shallow thumbprint into each.

Fill indents with a small scoop of strawberry jam.

Bake 10 to 12 minutes; cool completely.

Whisk powdered sugar and milk into glaze; drizzle over cooled cookies and top with sprinkles.