Preheat the oven to 350°F. Grease an 8x8 pan and set aside.
In a saucepan over medium heat, melt the butter and brown sugar, stirring constantly until smooth. Remove from the heat, and stir in the Biscoff Spread, stir until creamy and combined. Set mixture aside to cool.
In a large bowl, whisk together flour, baking powder, baking soda, salt, and cinnamon.
Add the egg to the Biscoff mixture and stir until smooth. Add the vanilla extract and stir to combine. Pour the mixture into the prepared dry ingredients, and stir until batter is smooth. Fold in white chocolate chips.
Transfer the batter to the prepared pan, spreading the batter evenly to the edges of the pan. Bake for 25 minutes or until the top is golden and the edges are slightly browned and a toothpick comes out clean. Remove blondies from oven and place them on a wire rack to cool. Once cooled, cut into squares and serve.