Preheat oven to 375 degrees. In a food processor, add your 4 cups of vanilla wafers and pulse until a fine meal forms. Then add in your 1 stick melted butter and sugar. Pulse to combine, about 10 seconds.
Line a 7x11 baking dish with heavy duty tin foil. Trick: turn the pan upside down and press the tin foil around the bottom of the dish. Then flip the pan back over and the foil will fall right inside. Spray with nonstick spray.
Press your vanilla wafer crust into the bottom of the pan, going up the sides just a little. Bake for 18 minutes.
While that's baking, combine your sweetened condensed milk and 3 tbsp butter in a small saucepan and heat until butter is melted. When the crust is done, pour this filling over the hot crust. Sprinkle with some of the chocolate chips and toffee bits. Bake for 16 minutes until filling is bubbly and looks golden brown.
When it's done, remove from oven and immediately spread the remaining chocolate chips over the top. Let sit for about 30 seconds. Using a spatula, spread the chocolate chips over the top. It's okay if they get pushed down a bit. Then top with the remaining toffee bits. Pressing down to ensure they stick.
Let cool completely at room temperature. About an hour or a little more. Can be stored at room temp but I prefer the fridge!