Line a baking sheet with parchment paper. Choose a size that lets you spread the yogurt about 1/4-inch thick.
In a bowl, mix the Greek yogurt, honey, vanilla, and a pinch of salt until smooth and slightly sweet.
Warm the Biscoff cookie butter in the microwave for 10–15 seconds until pourable.
Spread the yogurt mixture evenly over the lined tray.
Aim for even thickness so it freezes uniformly.
Drizzle the warm cookie butter over the yogurt. Use a knife or toothpick to swirl it for a marbled look.
Sprinkle crushed Biscoff cookies over the top. Add any optional toppings like mini chocolate chips or nuts.
Freeze for 2–3 hours, or until completely firm.
Break into pieces.
For clean edges, let it sit at room temp for 2 minutes, then cut with a sharp knife.
Enjoy right away or store as directed below.