Preheat your oven to 350°F (175°C). In a food processor, pulse together saltine crackers and milk chocolate toffee pieces until finely crumbed. Melt ½ cup of unsalted butter and mix with the crumb mixture until well combined. Press the mixture firmly into a pie pan, covering the base and sides evenly. Bake in the preheated oven for 10-12 minutes or until set. Let cool completely before proceeding.

In a medium saucepan over medium heat, melt ½ cup of unsalted butter and 1 cup of dark brown sugar together, stirring until combined and bubbly. Slowly whisk in 1½ cups of heavy cream, continuing to cook the mixture until it thickens and bubbles gently, about 5-7 minutes. Add a pinch of kosher salt and 1 teaspoon of vanilla extract, stirring well. Remove from heat and set aside.

In a mixing bowl, whisk together 4 egg yolks and 2 tablespoons of cornstarch. Gradually add about 1 cup of the hot butterscotch mixture to the egg yolks while continuously whisking to temper the eggs and prevent scrambling. Return the mixture to the saucepan and cook over medium heat, stirring frequently for another 3-5 minutes, until thickened.

Once thickened, pour the butterscotch pudding into the cooled saltine toffee crust, smoothing the surface with a spatula. Refrigerate for at least 2 hours until fully set and chilled.

In a mixing bowl, whip 1 cup of heavy cream with 2 tablespoons of powdered sugar until soft peaks form. Spread the whipped cream over the chilled butterscotch filling evenly.

Drizzle any reserved butterscotch sauce over the whipped cream or create swirls. Slice and serve chilled.