Preheat the oven to 350°F (175°C). Line a 9-inch cake pan with parchment paper and lightly grease the edges with non-stick spray.

In a large mixing bowl, combine the sugar, flour, cocoa powder, baking powder, baking soda, and salt. Whisk thoroughly to ensure even distribution of ingredients.

Add the eggs, milk, canola oil, and vanilla extract to the dry ingredients. Using an electric mixer, beat the mixture until smooth and well combined.

Gradually pour the boiling water into the batter while mixing on low speed. The batter will be thin—this is expected.

Transfer the batter into the prepared cake pan and bake for 25-27 minutes, or until a toothpick inserted in the center comes out clean. Allow the cake to cool for 20 minutes before transferring to a wire rack. Once fully cooled, level the top with a serrated knife and place the cake into the base of a 9-inch springform pan.

In a microwave-safe bowl, melt the semi-sweet chocolate chips with the cream cheese, stirring until smooth. Allow to cool slightly.

In a small bowl, mix cold water with unflavored gelatin, letting it soften for 1 minute. Add boiling water and whisk until the gelatin is fully dissolved.

In a separate bowl, whip heavy cream and powdered sugar until soft peaks form. Gently fold in the cooled chocolate mixture and dissolved gelatin until fully incorporated.

Spread the chocolate mousse evenly over the cake layer. Refrigerate while preparing the next layer.

In a small bowl, soften the unflavored gelatin in cold water for 1 minute. Heat ½ cup of heavy cream until boiling, then whisk in the gelatin until fully dissolved.

Pour the hot cream over the white chocolate chips, stirring until completely melted and smooth.

In a separate bowl, whip the remaining 1 cup of heavy cream until stiff peaks form. Gently fold the melted white chocolate mixture into the whipped cream until fully incorporated.

Spread the white chocolate mousse evenly over the chocolate mousse layer. Refrigerate for at least 1 hour before proceeding.

In a microwave-safe bowl, heat the heavy cream until boiling. Pour it over the semi-sweet chocolate chips, whisking continuously until a smooth ganache forms. Allow to cool until thick but still pourable.

Run a sharp knife around the edges of the springform pan and remove the ring. Pour the ganache over the top of the cake, letting it cascade down the sides.

While the ganache is still soft, press mini chocolate chips into the sides of the cake for decoration.

Return the cake to the refrigerator for at least 4 hours to allow the ganache to set fully.

Melt the white candy melts and drizzle over the top of the cake for an elegant finish.

Once the ganache has set, slice and serve. For the best texture and flavor, allow the cake to sit at room temperature for 10 minutes before slicing.