"For my friend's birthday, I wanted to make her a cookie butter (ie. speculoos or Biscoff®) cake. I couldn't find a recipe that I liked, so I just made one up. It was a great success, everyone who ate a slice kept coming back for seconds! The cake is best served chilled, so you may want to put it in the fridge or freezer for at least 30 minutes before serving (I like mine overnight)."
Preheat oven to 350 degrees F (175 degrees C). Spray a 10-inch springform pan with cooking spray.
Combine spice cake mix, 1 cup water, eggs, and vegetable oil in a large bowl; beat with an electric mixer on low speed until moistened, about 30 seconds. Add sweetened condensed milk, 1/4 cup cookie butter, 1 tablespoon vanilla extract, and pumpkin pie spice. Increase speed to medium and beat until batter is smooth, about 2 minutes.
Arrange slices from 1 pear on the bottom of the prepared pan. Pour batter on top.
Bake in the preheated oven until a toothpick inserted into the center comes out clean, 30 to 40 minutes. Allow to cool completely, about 30 minutes.
Melt 1 tablespoon butter in a large skillet over medium-high heat. Stir in remaining pear slices, 1/3 cup water, 1/4 cup honey, and cinnamon whiskey. Cook until pears are soft and the water has evaporated, 8 to 10 minutes. Remove from heat and let cool.
Combine cream cheese, heavy cream, confectioners' sugar, 3/4 cup cookie butter, 1/2 cup butter, 2 teaspoons honey, and 1 teaspoon vanilla extract in the bowl of a stand mixer fitted with the paddle attachment; beat until frosting is slightly stiff, 10 to 20 minutes.
Remove sides of the springform pan to release cake. Slice into three even layers; transfer middle and top layer to a flat work surface. Invert bottom layer and peel off base so pear slices are facing upward. Cover with middle cake layer; arrange pear and honey mixture evenly on top. Add top cake layer.
Spread frosting over the top and sides of the cake.