- Heat oven to 350F.
- Lightly grease an 8 or 9-inch nonstick round cake pan or coat lightly with cooking spray; set aside.
- Finely crush Biscoff Cookies; set aside.
- Melt butter; set aside to cool.
- Peel and core apples; cut into thin slices and set aside.
- Beat together eggs and 1/2 cup of the sugar in a medium bowl with a wooden spoon.
- Stir in butter.
- Stir in flour and crushed Biscoff Cookies; mix well and set aside.
- Cook remaining 1/2 cup sugar in a small skillet over medium heat until completely melted and golden brown, about 5 minutes, stirring occasionally.
- Immediately pour into prepared pan, tilting pan to evenly spread caramel.
- Arrange apples in concentric circles over hot caramel.
- Spread Biscoff Cookies mixture evenly over apples.
- Bake 40 minutes or until golden brown and center is set.
- Cool in pan on wire rack 5 minutes.
- Use a knife to loosen cake from edge of pan; invert onto a serving plate. Serve warm or at room temperature with ice cream if desired.
*Biscoff Cookies are available in 8.8 oz packages or individual .5 oz two-packs at www.shopbiscoff.com or through retailers nationwide.
**If self-rising flour is unavailable, use all-purpose flour plus 1 teaspoon baking powder and 1/4 teaspoon salt.