Preheat oven to 350°. Spray two medium (9 x 5) loaf pans with nonstick baking spray, or five mini loaf pans (5 ¾ x 3 ¼ x 2 ¼.)
In a medium bowl whisk together flour, cinnamon, baking powder, and salt. Set aside.
In the bowl of a stand mixer beat the butter and the sugars until light and fluffy, about two minutes. Mix in Biscoff spread. Add eggs one at a time mixing well after each addition, scraping down sides of bowl as needed. Add vanilla and sour cream and mix to combined. Add flour mixture mixing on low just until combined. Stir in white chocolate chips.
Spoon batter into prepared pans. Don’t fill more than ⅔ full. Bake for 50 minutes or until the center springs back when lightly pressed and toothpick comes out clean. (Bake 35-40 minutes for the mini loaves.)
Cool in pan 15 minutes on wire rack. Remove from pan and cool completely on wire rack before serving.