make the viennese Whirls
Preheat the oven to 200 °C / 390 °F (or 180 °C / 355 °F if you're using a convection oven). Add softened butter, powdered sugar, and tahini to a bowl. Using an electric mixer beat until the mixture is smooth. Add all-purpose flour, and cornstarch. Beat until just combined.TipFeel free to substitute tahini with softened butter.
Spoon the mixture into a piping bag fitted with a large star-shaped nozzle. Line a baking sheet with parchment paper. If all the cookies don't fit, do it in two batches. Pipe swirly circles 5 cm (2-inch) diameter onto the baking sheets making sure you don't overcrowd the cookies. Place the baking sheet with cookies in a freezer for 5 - 10 minutes - this way they will hold their beautiful shape. Place in the preheated oven. Bake for 10 minutes at 200 °C / 390 °F (or 180 °C / 355 °F if you're using a convection oven). Remove from the oven and transfer to a wire rack to cool completely.
Add strawberry marmalade to a saucepan and place over medium-high heat. Bring to a boil, then immediately remove from the heat and set aside for a couple of minutes to cool. The marmalade has to be thick. Spread a little marmalade on the flat side of the cookie and cover it with another cookie, to make a delicious cookie sandwich. Transfer the cookies to a serving plate, optionally sprinkle with some powdered sugar and serve. Keep in an airtight container, at room temperature, for up to 10 days.