Pre-heat oven to 350℉.
In a large bowl, mix to combine wet mixture - unsalted butter, granulated sugar, egg and vanilla extract.
In a separate bowl, bring together dry mixture - all purpose flour, baking powder, and salt. Mix well.
Add dry mixture into wet mixture. Using a spatula to combine everything.
Optional: cover bowl and refrigerate dough for 1-2 hours.
Roll dough into small 1 1/2 inch balls. Then use the ends of a rolling pin or thumb to make an indentation at the middle of the dough ball. Press halfway down but not all the way.
Press tops of cookies face down onto a bowl of white sugar sprinkles, and place them ~2 inch apart on the baking sheet.
Fill each of the indentation with strawberry jam.
Bake for 14-15 minutes.
Remove from oven let it cool on the baking sheet for a few minutes, then place them on cooling rack until they are completely cool.
Serve and enjoy!