Pre heat oven to 350°F
Cream together room temperature butter with icing sugar until creamy and fluggy.
Add in one egg and cream until combined.
Add in salt, vanilla, flour and corn starch. Mix until just combined.
Place 1 Tbsp dollops of dough on a cookie sheet, leaving about 2 inches apart.
Ising oyu index finger to make indents in each dough ball. Don't press all the way down to the baking tray otherwise the jam will spill through. TIP: wet your finger to prevent sticking. Add about ¼ tsp worth of jam in each indent.
Bake for 15 minutes or until edges are golden brown.