Chocolate Spider Web Layer Cake

I first saw this cake on, where else, but Katie's blog last year. I saved it and made SURE to make it this year. I did make an error when I made the glaze, which led it to become more of a frosting, but it was still delicious and so cute for Halloween! I noted my mistake in red, but had I followed directions, it would have been even easier to make.

Chocolate Spider Web Layer Cake
As seen on Good Things Catered

Ingredients
1 Hershey's Perfectly Chocolate Layer Cake
filled with Perfectly Chocolate Icing (I was in a hurry so I used a canned Pillsbury Funfetti frosting, which was already orange for Halloween. Good in a pinch)
1/4 c. heavy whipping cream
9 oz bittersweet chocolate
2 Tbsp unsalted butter, cut into small pieces
3 oz white chocolate

Directions:
-In small saucepan over medium low heat, heat whipping cream, stirring occasionally.
-Chop chocolate finely and place into large heat-proof bowl with butter (Here is where I made my error. I did not chop the chocolate finely enough and I forgot the butter. So it became more of a fudge frosting, which was still delish but NOT as easy as the glaze would have been)
-When whipping cream starts to come to a boil, remove from heat and pour over chocolate.
-Stir immediately and constantly until mixture becomes smooth.
-Let rest until thick enough to form a glaze, about 3 minutes.
-Meanwhile, place cake, on board over a wire rack over the sink (for clean-up's sake).
-Pour glaze over top of the cake and spread out evenly and over the edges with a spatula.
-In a disposable piping bag of microwave proof bag, heat white chocolate in microwave until melted.
-Cut tip off of bag and pipe a spiral onto the top of the cake, starting in the center.
-Starting in the center of the cake, drag a toothpick through the icing, toward the outside edge of the cake, every few inches, to form spiderweb decoration.
-Use remaining white chocolate to pipe spiders onto cake.
-Let icing cool completely before serving.