Place Oreo cookies (including filling) in a food processor and pulse until fine crumbs form, about 30–45 seconds. If you don't have a food processor, place cookies in a sealed plastic bag and crush with a rolling pin until finely ground.

Transfer crumbs to a mixing bowl and stir in melted butter and granulated sugar (if using) until the mixture resembles wet sand and holds together when pressed.

Press the crumb mixture evenly into the bottom and up the sides of a 9-inch pie pan (or 9-inch tart pan), using the bottom of a measuring cup or glass to compact the crust firmly and evenly (about 1/4–1/2 inch thick).

Chill the crust in the refrigerator for at least 15 minutes to set while you prepare the filling. For a firmer crust, bake at 350°F (175°C) for 8–10 minutes and cool completely before filling (optional).

Chocolate Filling

Place the chopped chocolate in a heatproof bowl and set aside.

In a small saucepan, heat 1 cup heavy cream over medium heat until it just begins to simmer and small bubbles form at the edges (do not boil).

Pour the hot cream over the chopped chocolate and let sit undisturbed for 2 minutes to soften the chocolate.

Gently whisk the mixture from the center outward until smooth and glossy. Stir in 2 tbsp butter, 1 tsp vanilla extract, and a pinch of salt until fully incorporated and the ganache is silky.

Pour the chocolate filling into the chilled prepared Oreo crust, smoothing the top with a spatula. Tap the pan gently on the counter to remove any air bubbles.

Allow the pie to set: refrigerate for at least 2 hours or until the ganache is firm to the touch. For best texture, chill 3–4 hours or overnight.

Whipped Cream & Garnish

Chill a mixing bowl and beaters in the freezer for 5–10 minutes if available (this helps the cream whip faster).

Pour 1 cup cold heavy cream into the chilled bowl. Add powdered sugar and 1 tsp vanilla extract.

Whip on medium-high speed with a hand mixer or stand mixer until soft peaks form (about 2–3 minutes). Be careful not to overwhip—stop once peaks hold their shape but are still creamy.

Once the chocolate filling is set, spread or pipe the whipped cream over the pie evenly. Reserve a few tablespoons of whipped cream if you want to pipe rosettes around the edge.

Sprinkle mini chocolate chips evenly over the whipped cream. If desired, press a few chips into the edge rosettes or sprinkle extra Oreo crumbs for contrast.

Return the pie to the refrigerator for 15–30 minutes to let the whipped cream firm slightly before serving.