Melt butter in a microwave-safe bowl and pour melted butter over Speculoos Cookie Powder. Stir to combine until all crumbs are moistened.
Press into a 9” pie pan using a spoon or measuring cup to compress crust. Set aside.
Combine white chocolate and heavy cream in a microwave-safe bowl. Microwave on high for 45-60 seconds until melted. Vigorously stir until all the chocolate is melted. Allow to cool for about 10 minutes.
Whip cream cheese on medium speed until light and fluffy for 2-3 minutes. Add Speculoos Cookie Butter and continue to beat until well mixed.
Add melted white chocolate and mix until combined.
Add the vanilla extract and heavy whipping cream, increase mixing speed to medium-high and whip for 2-3 minutes to add air into the batter.
Add marshmallow fluff into batter and mix thoroughly.
Pour batter onto the pie crust. Chill in the refrigerator for at least two hours. Serve chilled.