Preheat the oven to 180 degrees celsius.
Take a large bowl, put in the butter and sugar and beat it using an electric mixer until it is smooth. Then add in the egg, and beat it again. Next, add the flour and mix slowly just until these ingredients are blended well together.
Shape the dough into 1-inch balls and place them on baking sheets, at least 3 inches apart.
Moisten your thumb with water and gently press the center of each ball, making a hole about 1/2 inch wide and inch deep.
In a microwave, heat the jam until it is liquefied, then add 1/2 teaspoon of jam into these cookies.
Bake for 18-20 minutes until these cookies are golden brown around the edges.
Once cooked, transfer them to a wire rack, and let them cool.
Serve warm or store in an airtight container for 2-3 days.