Line 2 baking trays with baking (parchment) paper.
If you are using plain flour and baking powder sift or mix well to combine. Put aside.
Place the butter and sugar into a large mixing bowl. Use and electric mixer and beat until light and fluffy. (See notes below for hand mixing tips).
Add the egg and vanilla mix until combined.
Add the flour and use a wooden spoon or clean hands to work the flour into the butter mixture.
Divide the mixture evenly into 40 pieces and roll into balls.
Place on the prepared trays spacing them about 5 cm (2 inches) apart. Use your finger to make a hollow in the centre of each ball about halfway down.
Use a teaspoon to drop a small amount of jam into each hollow.
Place the trays in the fridge and chill for 30 minutes.
About 10 - 15 minutes before baking preheat oven to 170°C (340°F).
Bake the cookies for about 10 – 15 minutes or until they become lightly golden.
Remove from the oven and leave on the trays for about 10 minutes, then transfer to a wire rack to cool completely.