In a bowl, stir together the Greek yogurt, Biscoff cookie butter, honey, vanilla, and salt until smooth and creamy.
Add the protein powder and oat flour. Stir until a thick, cookie-butter-batter texture forms.
Gently fold in white chocolate chips or crushed Biscoff cookies.
You can eat it immediately, or chill for 10 to 15 minutes if you want a thicker texture.