• Brew a very strong coffee or espresso. Heat the milk in the microwave for 1 minute; it should feel fairly hot to the touch but not hot enough to burn your finger. While the milk is heating, add the cookie butter to your hot coffee and mix until it dissolves (you can use a small whisk, fork, or handheld frothing wand). Next, add the brown sugar and vanilla extract, stirring again until fully dissolved.
• Pour the hot milk into a mason jar and close the lid. Shake the jar for 1-2 minutes until foam begins to form, and remember to open the lid after the first 15-20 seconds to let some excess heat escape. If you have a handheld frothing wand or a coffee machine with a frothing feature, you can use that to froth the milk until a foam forms (some machines allow you to hot froth, so you can skip heating the milk if yours does this).
• Pour the frothed milk into the coffee mixture, using a spoon or the mason jar lid to hold back the foam.

To Garnish

• Add melted cookie butter and garnish with Biscoff cookies. For the Biscoff garnish, you can crumble cookies on top of the whipped cream, dip whole cookies into the whipped cream, or arrange them around the top edge of the glass with extra melted cookie butter. A drizzle of caramel also adds a nice touch.