Start by preparing the dough. Cream the softened butter and sugar together for about 3 to 5 minutes until it's light and fluffy.

Sift the flour into the creamed butter mixture and gently mix until you form a soft dough.

Divide the dough in half and shape each portion into a disk. Wrap them in parchment paper and roll each to 3/8 inch thickness. Chill in the refrigerator for about 30 minutes.

Take the dough out and peel off the top parchment layer. Lightly dust with flour. Use a 2-inch round cookie cutter to cut out cookies for the base. For the tops, use a smaller round cutter to cut a window in half of the cookies.

Preheat your oven to 320°F. Arrange the cookie shapes on a baking sheet and bake for 12 to 15 minutes until they turn golden brown.

Let the cookies cool. Fill a piping bag with buttercream and pipe it along the rim of the bottom cookie. Place the cut-top piece over it, pressing gently.

If you want to thicken your jam, heat it in a pot for 1 minute. Mix in cornflour, whisk for 4 minutes until thick. Cool it before piping into the center of the assembled cookies.

Sprinkle some powdered sugar on the cookies for an extra touch. Enjoy these fabulous treats with a nice cup of tea or coffee!