Preheat your oven to 350°F (175°C). Lightly grease a 9-inch tart pan with a removable bottom.

In a food processor, pulse the chocolate sandwich cookies (with cream removed) until finely ground into crumbs. Transfer the crumbs to a medium bowl.

Pour the melted butter over the cookie crumbs and mix until well combined and the mixture resembles wet sand.

Press the cookie mixture evenly into the bottom and up the sides of the prepared tart pan. Use the bottom of a glass or your fingers to firmly press it down for an even crust.

Bake the crust for 10-12 minutes, or until fragrant and slightly firm. Let it cool completely on a wire rack while you prepare the filling.

Place the finely chopped dark chocolate in a heatproof bowl. Add the cold butter pieces, vanilla extract, and pinch of salt to the bowl.

In a small saucepan, heat the heavy cream over medium heat until it just begins to simmer around the edges (do not bring to a rolling boil).

Immediately pour the hot cream over the chocolate mixture. Let it sit undisturbed for 5 minutes to allow the chocolate to melt.

After 5 minutes, gently whisk the mixture starting from the center and slowly expanding outwards, until completely smooth, glossy, and emulsified.

Pour the ganache filling into the cooled chocolate cookie crust. Gently tap the tart pan on the counter a few times to release any air bubbles and ensure an even surface.

Melt the white chocolate with the neutral oil in a small microwave-safe bowl in 15-second intervals, stirring after each, until smooth. Alternatively, melt over a double boiler.

Transfer the melted white chocolate to a small piping bag (or a small Ziploc bag with a tiny corner snipped off).

Working quickly while the ganache is still warm and pourable (if it's started to set, you can gently warm the surface with a hairdryer on low for a few seconds), pipe concentric circles of white chocolate onto the ganache, starting from the center and moving outwards.

Take a toothpick or skewer and drag it from the center of the tart outwards through the white chocolate circles, creating lines that resemble a spiderweb. Repeat this process every 1-2 inches around the tart.

Once the spiderweb design is complete, transfer the tart to the refrigerator and chill for at least 3 hours, or until the ganache is fully set and firm.

Once firm, carefully remove the tart from the pan. For best results, allow the tart to sit at room temperature for 10-15 minutes before slicing and serving to ensure the ganache is creamy.