Preheat oven to 175°C (350°F) top and bottom heat. Line a baking tray with baking paper.
Add all the dry ingredients to a mixing bowl. Add the butter and knead with your hands until the dough comes together into a ball (don't over knead).
Roll the dough into about 25 round balls. After rolling each cookie, immediately use your thumb or the back end of a mixing spoon to make a deep indentation in each cookie.
Space the cookies well apart on the baking sheet, as they will spread a bit in the oven. Fill each indentation with jam.