Place the cookies into a food processor. Pulse until they are the consistency of crumbs.

Add the butter and powdered sweetener and pulse again, just until uniform and crumbly.

Chill the dough in the fridge for about 15 minutes, until it's less sticky and easy enough to work with.

Press the cookie dough into the bottom of the pan and up the sides of a 9-inch (23 cm) pie pan, to form the crust.

Freeze the crust for 20 minutes.

Meanwhile, in a large, deep bowl, beat together the peanut butter, cream cheese, and powdered sweetener for about 2 minutes, until fluffy. Beat in the vanilla extract. Beat in approximately 6 tablespoons (88 mL) heavy cream, 1 tablespoon (15 mL) at a time, until it reaches the consistency of thick frosting. The amount of cream you need will vary depending on how thick your peanut butter was, so just keep adding 1 tablespoon (15 mL) at a time until it's like a thick frosting.

In a second bowl, beat 3/4 cup (177 mL) heavy cream, until stiff peaks form. Fold the whipped cream into the peanut butter mixture.

Transfer the filling into the pie pan over the crust.

Freeze for at least 1 hour, until firm. Keep frozen, but let it sit on the counter to soften slightly if it's too hard right out of the freezer (similar to an ice cream cake). If you like toppings, you can add melted peanut butter drizzle, melted chocolate drizzle, and/or more cookies crumbled on top (all of these are optional).