Add 1 tablespoon of cookie butter to the bottom of a mug.
Brew hot espresso or strong coffee directly over the cookie butter. Stir it with a spoon until fully melted and smooth.
Fill a glass with ice and add the 1/2 cup of milk. Pour the cookie butter coffee over the top. Note: if you like your coffee sweet, add flavored syrup at this stage too.
To make the foam, add 1 tablespoon of cookie butter, 2 tablespoons of milk, 2 tablespoons of heavy cream, and the syrup (if using) to a small jar or cup. Use a fork or small whisk to break up the cookie butter. No need to make it completely smooth at this stage.
Use a handheld frother or a hand mixer to whip the mixture. At first, the cookie butter will lump up, but after a few seconds it will come together and smooth out.
Whip for 60–90 seconds, until thickened, creamy and pourable (it will be thinner than whipped cream). Set aside.
Pour the cookie butter foam over the latte. Serve immediately.