1. Using an electric hand mixer or a stand mixer with a whisk attachment, beat together the pudding mix, dark cocoa powder, pinch of salt, 1 teaspoon of vanilla extract, milk, and 1.5 cups heavy cream until smooth, combined, and starting to thicken. If there are noticeable lumps, strain the mixture through a fine mesh strainer.
2. In a microwavable bowl in the microwave or on the stove in a small pot, gently melt the 4 ounces of chocolate (about 1 minute in the microwave). Stir until smooth. Beat the melted chocolate into the pudding mixture until smooth, combined, and a thick pudding-like consistency.
3. For the whipped cream topping, use an electric hand mixer or stand mixer fitted with a whisk attachment to beat together the 1 3/4 cup heavy cream, pinch of salt, 1/2 teaspoon vanilla bean paste, and powdered sugar until stiff peaks form.
4. To assemble, layer half of the Biscoff cookies in a 9x9 inch pan, then top the cookies with half of the pudding mixture. Repeat with the remaining Biscoff cookies and pudding, and then top the pudding with the whipped cream. Optionally, shave chocolate on top of the whipped cream.
5. Cover the icebox cake and place it in the fridge to set for six hours or overnight to allow the cookies to soften. Then scoop and serve.
